Unit 1:Introduction to Unit 1:Introduction to ForensicsForensics

WHAT IS FORENSIC SCIENCE?WHAT IS FORENSIC SCIENCE?..

The The word word forensicforensic is is based on a Latin word based on a Latin word meaning "pertaining to law."meaning "pertaining to law."

Forensic science is the application of Forensic science is the application of science to law. science to law.

In its broadest sense, forensic science In its broadest sense, forensic science becomes part of almost every law. becomes part of almost every law.

If a can of soda is labeled caffeine-free and If a can of soda is labeled caffeine-free and 12 fl oz, this is a legal claim, which is 12 fl oz, this is a legal claim, which is controlled by the Food and Drug controlled by the Food and Drug Administration (FDA). The FDA can check if Administration (FDA). The FDA can check if the beverage manufacturer is following the the beverage manufacturer is following the law by having its scientists measure the law by having its scientists measure the caffeine content and volume.caffeine content and volume.

QuestionsQuestions

1. what color coffee mug was in the 1. what color coffee mug was in the picturepicture

2. When was the deadline?2. When was the deadline?3. What time was the clock on the 3. What time was the clock on the

wall set?wall set?4.How many sticky notes were on the 4.How many sticky notes were on the

whiteboard?whiteboard?5. What color was the victims t shirt5. What color was the victims t shirt

6. Which of the following was not in the 6. Which of the following was not in the picture? A. stapler B. trash can c. penpicture? A. stapler B. trash can c. pen

D. printerD. printer7. What was the name on the plaque on 7. What was the name on the plaque on

the desk?the desk?8. How many plants were in the picture.8. How many plants were in the picture.9. Where was the book in the picture?9. Where was the book in the picture?10. What was on the floor? 10. What was on the floor?

AnswersAnswers

1. yellow 9. on box on right1. yellow 9. on box on right2. today 10. backpack2. today 10. backpack3. 11:053. 11:054. 74. 75. blue5. blue6. stapler6. stapler7. brian castillo7. brian castillo8. 28. 2

http://http://forensics.rice.edu/html/http://http://forensics.rice.edu/html/observation.html#observation.html#

Part 1Part 1

Eyewitness Memory

Wow! That’s extremely high!

““I know that face!”I know that face!”

Face-recognition rates are usually around 90%

So eyewitness memory must

be pretty accurate…right?

No, this 90% accuracy rate does not

apply to a criminal’s face

Why isn’t eyewitness Why isn’t eyewitness memory very accurate?memory very accurate? Witness FactorsAge

Exposure Duration

Race

Confidence

Reaction Time

Weapon Focus

System Variables

Verbal Overshadowing

Lineup

Post event information

Post-identification feedback

Witness factor:Witness factor: AgeAge

Children are unreliable witnesses

Adults over 60 are more likely to make false identifications

Witness Factor:Witness Factor: Exposure DurationExposure Duration

The longer the exposure…the more accurate the identification

BUT…the longer the exposure,

the more confident the witness,

even if wrong

Witness Factor:Witness Factor: RaceRace

Better at recognizing own-race faces

Recognize own-race faces holistically rather than by features

Holistic recognition comes from experience with or exposure to other races

Witness Factor:Witness Factor: ConfidenceConfidence

Confidence is a weak predictor of eyewitness accuracy

Confidence Accuracy

Witness Factor:Witness Factor: Reaction TimeReaction Time

If an eyewitness comes to a decision within a 10-12 second window, they are more likely to be accurate

In combination with confidence, 90% accurate

Witness Factor:Witness Factor: Weapon FocusWeapon Focus

A witness confronted with a weapon tends to focus on the weapon rather than the perpetrator’s face.

Flashbulb memoryChallenger Study

High arousal did not lead to better memory

System Variable:System Variable: Verbal OvershadowingVerbal Overshadowing

Verbally describing a face can impair future attempts to identify the face

Individuals who first described a face were 1.27 times more likely to misidentify the face from a lineup

System Variable:System Variable: Lineup FairnessLineup Fairness

People in the lineup should be selected based on similarity to the perpetratorNo individual should stand out in the

lineup

The interviewer should not “favor” any individual in the lineup

You've discovered a problem with the crime scene photos You've discovered a problem with the crime scene photos from a recent case.from a recent case.

Someone has tampered with your crime scene!Someone has tampered with your crime scene!

See how many differences you can spot between these two See how many differences you can spot between these two photographs of the same crime scenephotographs of the same crime scene

Which is the correct penny?NOTE: You cannot look at a real penny!

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

There was nothing Leon, the driver, could do about the

impending crash of the car he was driving. Leon knew the car would be completely demolished

in the crash. After the crash Leon didn’t have a scratch on

him. How can that be?

Leon was driving a remote control car.or

He was playing a video game.

Hint: Notice the bones in the trash.

An inconsiderate slob dumped trash on Rachel Rabbit's lawn.

One of these two suspects is guilty. Slylock Fox foundevidence that may identify the loathsome litterbug.

What did Slylock observe to help him identify the trash tosser?

Slylock found bones in the trash.

The bull is an herbivore and only eats plants.

The raccoon is an omnivore and eats both plants and animals. The raccoon is the

trash tosser.

HISTORYHISTORY

In modern crime solving there In modern crime solving there are normally two avenues of are normally two avenues of investigation, one involving investigation, one involving people and the other involving people and the other involving physical evidencephysical evidence..

1814 Mathieu Orfila1814 Mathieu Orfila: Writes the : Writes the first scientific paper on the first scientific paper on the diction of poisons. He latter diction of poisons. He latter published articles on the published articles on the classification of poisons classification of poisons ( ( toxicology)toxicology) and is known as the and is known as the father of toxicology. father of toxicology.

1879 Alphonse Bertillon1879 Alphonse Bertillon : :publishes his publishes his first book on first book on anthropometryanthropometry, , a personal a personal identification method based on 11 body identification method based on 11 body measure ments. measure ments.

This was the first system of personal This was the first system of personal identification used by the police. After a identification used by the police. After a famous case (william west) showed that famous case (william west) showed that two different people had the same two different people had the same anthropometry measurements, the sys tem anthropometry measurements, the sys tem was abandoned and fingerprints became was abandoned and fingerprints became the preferred tool.the preferred tool.

1887 1887 Arthur Conan Doyle:Arthur Conan Doyle: publishes his publishes his first Sherlock Holmes novel, first Sherlock Holmes novel, A Study in A Study in ScarletScarlet....

Francis GallonFrancis Gallon (1892): (1892):publishes the book publishes the book FingerprintFingerprints, s, which helpswhich helpspolice departments use fingerprints as a police departments use fingerprints as a means of personalmeans of personalidentification. In the book, Gallon explains identification. In the book, Gallon explains the many different characteristics of the many different characteristics of fingerprints and how they can combinefingerprints and how they can combineto form a unique print for each person. to form a unique print for each person.

Hans GrossHans Gross (1893) (1893)publishes the bookpublishes the book Criminal InvestigationCriminal Investigation, , whichwhichshows how the police can use science to shows how the police can use science to help in criminal inves tigations. Hans Gross help in criminal inves tigations. Hans Gross is considered by many to have been the is considered by many to have been the first truefirst true criminologist.criminologist.

Paul Jeserich;( 1898)Paul Jeserich;( 1898) develops forensic develops forensic chemistry.chemistry.

Karl Landsteiner:Karl Landsteiner: (1901) (1901)discovers the discovers the ABO blood groups.ABO blood groups.

19081908: : The U.S. Bureau of Investigation The U.S. Bureau of Investigation (BOI) is formed with 34 agents.(BOI) is formed with 34 agents.

1910 Albert Osborn1910 Albert Osborn publishes the publishes the book book Questioned DocumentsQuestioned Documents, , which explains the scientific which explains the scientific analysis of a suspected docu ment. analysis of a suspected docu ment. A questioned document is one of A questioned document is one of uncertain origin. The methods uncertain origin. The methods developed by Osborn are still in developed by Osborn are still in use today in the examination of use today in the examination of counterfeiting, alteration, counterfeiting, alteration, obscuring, and obliteration of obscuring, and obliteration of written instruments.written instruments.

1910 Edmond Locard1910 Edmond Locard establishes establishes a crime laboratory in the police a crime laboratory in the police department in Lyon, France. he department in Lyon, France. he is referred to as the “father of is referred to as the “father of forensic science.” His forensic science.” His observation that “observation that “Every contact Every contact leaves a trace”leaves a trace” is one of the is one of the guiding principles of forensic guiding principles of forensic sciencescience..

1915 Leone Lattes1915 Leone Lattes: discovers a : discovers a method for typing dried method for typing dried bloodstains. Based on the bloodstains. Based on the pioneering work of typing whole pioneering work of typing whole blood done by Karl Landsteiner, blood done by Karl Landsteiner, Lattes developed a method to type Lattes developed a method to type dried bloodstains. The method is dried bloodstains. The method is so sensitive that it has been used so sensitive that it has been used to determine the blood types of to determine the blood types of mummies.mummies.

The first crime laboratory in the The first crime laboratory in the United States is set up as part of United States is set up as part of die Los Angeles Police die Los Angeles Police DepartmentDepartment..

: New York City establishes the : New York City establishes the Bureau of Forensic BallisticsBureau of Forensic Ballistics run runby C. E. Waite, Calvin Goddard, by C. E. Waite, Calvin Goddard, Philip Gravelle, and JohnPhilip Gravelle, and JohnFisher.Fisher.

1929 Calvin Goddard1929 Calvin Goddard: considered the : considered the ““father of firearms identificationfather of firearms identification,” ,” matches the bullets recovered from matches the bullets recovered from the St. Valentine’s Day Massacre to the St. Valentine’s Day Massacre to the weapons from which they were the weapons from which they were fired. He establishes the use of the fired. He establishes the use of the comparison microscope for bullet comparison microscope for bullet identification. Goddard is credited with identification. Goddard is credited with making the first match of a bullet from making the first match of a bullet from a murder victim with a suspect’s gun.a murder victim with a suspect’s gun.

MILESTONES IN FIREARMS MILESTONES IN FIREARMS IDENTIFICATIONIDENTIFICATION

18351835 Henry Goddard Henry Goddard

First successful murderer identification from First successful murderer identification from bullet removed from victim’s bodybullet removed from victim’s body

18891889 Professor Lacassagne identified grooves on a Professor Lacassagne identified grooves on a removed bullet removed from a corpse and removed bullet removed from a corpse and matched it to a suspect’s weaponmatched it to a suspect’s weapon

18981898 Jeserich took microphotographs of fatal and Jeserich took microphotographs of fatal and test bullets test bullets

He testified the defendant’s revolver fired He testified the defendant’s revolver fired the fatal bulletthe fatal bullet

19261926 Calvin Goddard was most responsible for Calvin Goddard was most responsible for raising firearm identification to a scienceraising firearm identification to a science

1-15

19321932 :The U.S. BOI establishes a :The U.S. BOI establishes a forensic crime laboratory, which will forensic crime laboratory, which will become the center of forensic become the center of forensic analysis and research in the United analysis and research in the United States.States.

1935 1935 :The BOI changes its name to :The BOI changes its name to the Federal Bureau of Investi gation the Federal Bureau of Investi gation (FBI).(FBI).

1953 Paul Kirk:1953 Paul Kirk: publishes the book publishes the book Crime Investigation.Crime Investigation.

LOCARD'S PRINCIPLELOCARD'S PRINCIPLE In 1910 Edmond LocardIn 1910 Edmond Locard :persuaded the police :persuaded the police

department of Lyon, France, to hire him as department of Lyon, France, to hire him as their first forensic scientist. their first forensic scientist.

They also provided him with two assistants They also provided him with two assistants and some space in the attic of police and some space in the attic of police headquarters to build a makeshift laboratory. headquarters to build a makeshift laboratory.

He was quickly able to help them solve many He was quickly able to help them solve many famous cases by using science to analyze the famous cases by using science to analyze the physical evidence. physical evidence.

He solved a case involving the counterfeiting He solved a case involving the counterfeiting of gold coins by analyzing metal scrapings on of gold coins by analyzing metal scrapings on the suspect's clothing, a case of strangulation the suspect's clothing, a case of strangulation by analyzing fingernail scrapings from the vic by analyzing fingernail scrapings from the vic tim, and countless murders by analyzing tim, and countless murders by analyzing fingerprints.fingerprints.

Locard's principleLocard's principle can best can best be stated as "be stated as "Every contact Every contact

leaves a trace."leaves a trace."

When asked to help the police with an When asked to help the police with an investigation, one of the first things investigation, one of the first things Locard asked for was the suspect's Locard asked for was the suspect's clothing.clothing.

He hung the clothing over a clean piece He hung the clothing over a clean piece of white paper and carefully brushed it of white paper and carefully brushed it to remove any trace evidence adhering to remove any trace evidence adhering to the fabric. The physical evidence was to the fabric. The physical evidence was then analyzed and used to determine then analyzed and used to determine with what the suspect had been in with what the suspect had been in contact.contact.

Physical evidence Physical evidence triangletriangle

People ( People ( interrogationinterrogation ofof suspects/ witnesses)suspects/ witnesses)

Flow of Flow of

Investigation Evidence Investigation Evidence ( collection, ( collection,

analysis)analysis)

ROLE OF A FORENSIC ROLE OF A FORENSIC SCIENTISTSCIENTIST

The forensic scientist is one part of The forensic scientist is one part of the criminal justice system whose the criminal justice system whose function is to analyze physical function is to analyze physical evidence.evidence.

To do this, he or she must be an To do this, he or she must be an expert in some scientific area that is expert in some scientific area that is used in the investigation of crime.used in the investigation of crime.

Read case: Norman Thorne (cause of Read case: Norman Thorne (cause of death) forensic detective book)death) forensic detective book)

In the past, most forensic scientists In the past, most forensic scientists had college degrees in chemistry, had college degrees in chemistry, biology, or physics, became experts in biology, or physics, became experts in their fields by completing an their fields by completing an apprenticeship program where they apprenticeship program where they worked in a crime lab with an worked in a crime lab with an experienced forensic scientist until experienced forensic scientist until they learned their trade. they learned their trade.

Now a days many for scientists Now a days many for scientists graduate from college with specialized graduate from college with specialized 4-year degree forensic science.4-year degree forensic science.

When evidence is brought to the crime When evidence is brought to the crime lab, it is the role of thelab, it is the role of the forensic forensic scientist to analyze it and give the scientist to analyze it and give the conclusions to the investigator. These conclusions to the investigator. These conclusions could involve the conclusions could involve the identification, comparison, probability, identification, comparison, probability, and reliability of the results.and reliability of the results.

Often, the forensic scientist must Often, the forensic scientist must testify in court about the results of an testify in court about the results of an analysis the carried out.analysis the carried out.

Sometimes they are called to Sometimes they are called to testify about an analysis more than testify about an analysis more than a year before. a year before.

This is why it is important for the to This is why it is important for the to keep a good laboratory notebook keep a good laboratory notebook and document everything_that is and document everything_that is done. These notes help refresh the done. These notes help refresh the forensic scientist's memory well as forensic scientist's memory well as document all aspects of the document all aspects of the analysis.analysis.

A forensic scientist testifies at a A forensic scientist testifies at a trial as an trial as an expert witnessexpert witness, ,

Unlike an ordinary witness, an Unlike an ordinary witness, an expert witness can give an expert witness can give an opinion. opinion.

The The courts allow experts in courts allow experts in the the field to anafield to analyze the evidence and lyze the evidence and explain their results to the court.explain their results to the court.

The role of the forensic scientist to The role of the forensic scientist to educate the jury about the sci ence educate the jury about the sci ence behind the analysis so that they behind the analysis so that they have a better understanding of the have a better understanding of the significance of the results. A judge significance of the results. A judge determines who can act as an determines who can act as an expert witness. It is up to the jury expert witness. It is up to the jury to decide how much weight to give to decide how much weight to give the evidence and whether or not to the evidence and whether or not to believe the expert.believe the expert.

The forensic scientist can also be The forensic scientist can also be asked to train police officers asked to train police officers about evidence types, about evidence types, recognition, and collection and recognition, and collection and the capabili ties of the crime lab.. the capabili ties of the crime lab.. It is the job of the forensic It is the job of the forensic scientist to keep the scientist to keep the investigators in the field current. investigators in the field current.

While the majority of a forensic While the majority of a forensic scientist's time is spent scientist's time is spent analyzinanalyzing g physical evidencephysical evidence, they are also , they are also responsible for testifyingresponsible for testifying about about these results and training the these results and training the people who collect evidence. people who collect evidence. Added to these responsibilities is Added to these responsibilities is the requirement to keep current the requirement to keep current with advances in their field of with advances in their field of expertise.expertise.

CAREERS IN FORENSIC CAREERS IN FORENSIC SCIENCESCIENCE

Two more reasons for the Two more reasons for the popularity of the field include: popularity of the field include:

1) the number of jobs available 1) the number of jobs available 2)the degree of satisfaction with 2)the degree of satisfaction with

the work.the work.

Forensic science has become a Forensic science has become a popular career choice, driven not popular career choice, driven not only by media attentiononly by media attention but also but also by the expansion of job by the expansion of job opportuni ties.. The publics' opportuni ties.. The publics' interest in forensics is interest in forensics is increasing, and the prestige of increasing, and the prestige of the position is at an all-time the position is at an all-time high.high.

2002 report by the American 2002 report by the American Chemical Society in Chemical Society in Chemical and Chemical and Engi neering News (C&EN) Engi neering News (C&EN) stated: stated: Experts predict that more than Experts predict that more than 10,000 new forensic scientists will 10,000 new forensic scientists will be needed over the next decade to be needed over the next decade to address an exponentially address an exponentially expanding backlog of DNA expanding backlog of DNA evidence.—you can't put a price tag evidence.—you can't put a price tag on that."on that."

Another reason for the rapid Another reason for the rapid increase in the number of crime increase in the number of crime labs is based on the U.S. labs is based on the U.S. Constitution. Constitution.

The Sixth Amendment The Sixth Amendment guarantees the right of the guarantees the right of the accused to a fair and speedy accused to a fair and speedy trial. Specifically it says:trial. Specifically it says:

The majority of all evidence sent to a crime The majority of all evidence sent to a crime lab is drug-related. A forensic scientist must lab is drug-related. A forensic scientist must analyze it before the accused can be tried. analyze it before the accused can be tried.

The identity of the drug as well as the The identity of the drug as well as the quantity affect what the charges against quantity affect what the charges against the suspect will be.. the suspect will be..

The quantity is also important, as this can The quantity is also important, as this can change the charges from a misdemeanor to change the charges from a misdemeanor to a class A1 felony. In addition, advances in a class A1 felony. In addition, advances in science, such as in forensic DNA, have science, such as in forensic DNA, have greatly increased the amount of evidence greatly increased the amount of evidence that can be submitted to the crime lab for that can be submitted to the crime lab for analysisanalysis

SPECIALIZED FORENSICS SPECIALIZED FORENSICS SCIENCE CAREERSSCIENCE CAREERS

Some forensic scientists obtain Some forensic scientists obtain specialized or advanced degrees specialized or advanced degrees in preparation for certain forensic in preparation for certain forensic careers. careers.

These fields include medi cine, These fields include medi cine, toxicology, odontology, toxicology, odontology, pathology, psychiatry, pathology, psychiatry, engineering, entomology, and engineering, entomology, and anthropology. anthropology.

These specialties are of great use in forensic These specialties are of great use in forensic science and are often in high demand. science and are often in high demand. Initially, a coroner investigated any death Initially, a coroner investigated any death that was deemed suspi cious. that was deemed suspi cious.

The word The word coronercoroner comes comes from a Latin word from a Latin word meaning "from the crown." This meant that meaning "from the crown." This meant that the coroner was an official, appointed by the the coroner was an official, appointed by the king, whose job was to determine the cause king, whose job was to determine the cause of a sudden or unex pected death.. of a sudden or unex pected death..

Some states required coroners to Some states required coroners to be physicians, but others did not.be physicians, but others did not.

Sometimes an undertaker took Sometimes an undertaker took the position since they already the position since they already had a hearse and knew what to do had a hearse and knew what to do with a dead body.with a dead body.

The coroner system has gradually The coroner system has gradually been replaced by the been replaced by the medical medical examiner systemexaminer system. .

A A medical examinermedical examiner is a physician who is a physician who is autho rized by state statute to is autho rized by state statute to investigate sudden, unexpected, investigate sudden, unexpected, violent, suspicious, or unnatural deaths violent, suspicious, or unnatural deaths of persons within the state. The pur of persons within the state. The pur pose of this investigation is to detect pose of this investigation is to detect the cause and manner of death. From the cause and manner of death. From this, the medical examiner can this, the medical examiner can determine whether there was a determine whether there was a homicide or whether a threat to public homicide or whether a threat to public safety exists.safety exists.

A forensic pathologistA forensic pathologist is a is a physician with specialized physician with specialized training in determining the training in determining the cause of death and in forensic cause of death and in forensic science.science.

A pathologist aids a forensic A pathologist aids a forensic investigation by providing investigation by providing infor mation uncovered during infor mation uncovered during examination of the body.examination of the body.

One important piece of information is One important piece of information is the time of death, which can be the time of death, which can be

determined by several methodsdetermined by several methods..

The time since death is always an The time since death is always an estimate be cause it is based on estimate be cause it is based on many variables that cannot be many variables that cannot be controlled exactly. For this reason controlled exactly. For this reason a range of time is normally given. a range of time is normally given. This estimate of how long a This estimate of how long a person has been dead is called person has been dead is called the the postmortem interval (PMI).postmortem interval (PMI).

Algor mortisAlgor mortis is the process by is the process by which the body cools after death which the body cools after death as a result of loss of heat to the as a result of loss of heat to the surroundings.surroundings.

A A nomographnomograph is a diagram that allows is a diagram that allows a complicated mathematical a complicated mathematical relationship to be solved simply with a relationship to be solved simply with a ruler. ruler.

The time of death nomograph shown in The time of death nomograph shown in Figure can be used to estimate the Figure can be used to estimate the time of death based on the deep rectal time of death based on the deep rectal temperature of the body, surrounding temperature of the body, surrounding air temperature, body weight, and air temperature, body weight, and various other correction factors such various other correction factors such as the pres ence of clothing and as the pres ence of clothing and submersion in water.submersion in water.

Table 2.1 shows correction Table 2.1 shows correction factors used to account for factors used to account for nonstandard conditions such as nonstandard conditions such as clothing, air movement, wet clothing, air movement, wet clothing, and in water. The clothing, and in water. The correction factor is multiplied by correction factor is multiplied by the body mass to give a better the body mass to give a better estimate of how long the person estimate of how long the person has been dead.has been dead.

TABLE 2.1 Correction Factors for Body Weight in Estimating Time of Death

Wet Clothing or Wet Body Surface Condition of Condition of Air Water Correction Factor

Naked Flowing 0.35

Naked Still 0.5

Naked Moving 0.7

One or two thin layers Moving 0.7

Dry Clothing or Dry CoveringCondition ofAir Correction Factor

Naked Moving 0.75

One or two thin layers Moving 0.9

Naked Still 1.0

One or two diin layers Still 1.1

Two or three thin layers Still 1.2

One or two thin layers Moving or still 1.2

Three or four thin layers Moving or still 1.3

More than four thin layers Moving or still 1.4

Thick bedspread and clothing combined Moving or still 2.4

See HandoutSee Handout

Figure 2.2 shows an example of this Figure 2.2 shows an example of this sort. Suppose that the body was that sort. Suppose that the body was that of a 100-kg male. The rectal of a 100-kg male. The rectal temperature was 25.0°C, and the temperature was 25.0°C, and the ambient temperature was 10.0°C. The ambient temperature was 10.0°C. The body was found naked, and the air body was found naked, and the air was still (so the correction factor is was still (so the correction factor is 1.0).1.0).

body mass = body mass = 100 kg x 1.0 = 100kg100 kg x 1.0 = 100kg

FIGURE 2.2 explainedFIGURE 2.2 explained Draw a straight line from 25 on the rectum Draw a straight line from 25 on the rectum

temperature scale to 10 on the ambient temperature temperature scale to 10 on the ambient temperature scale.scale.

Mark the point where the drawn line intersects the Mark the point where the drawn line intersects the printed diagonal line running down from the top of printed diagonal line running down from the top of the rectum temperature scale. Next, draw a line from the rectum temperature scale. Next, draw a line from the center of the circle (on the lower left of the the center of the circle (on the lower left of the figure) through the intersec tion point you marked. figure) through the intersec tion point you marked.

The point where the line intersects the 100 kg arc The point where the line intersects the 100 kg arc indicates the hours since death can be read as about indicates the hours since death can be read as about 19.0 h. Since the line intersects the outer arc in the 19.0 h. Since the line intersects the outer arc in the 2.8 region, this means there is a 95% level of 2.8 region, this means there is a 95% level of certainty that the estimate is correct ±2.8 h. This certainty that the estimate is correct ±2.8 h. This puts the time of death between 16.2 and 21.8 h ago.puts the time of death between 16.2 and 21.8 h ago.

Most pathologists use the exact formula Most pathologists use the exact formula and enter the data into a computer. This and enter the data into a computer. This formula, where "T" stands for temperature formula, where "T" stands for temperature (°C), "t" stands for time, and "e" stands for (°C), "t" stands for time, and "e" stands for the mathematical constant, isthe mathematical constant, is

(T -T (T -T )/(37.2-r ) = 1.25^-)/(37.2-r ) = 1.25^-0.25^°0.25^°

v rectum ambient'' vv rectum ambient'' v ambient'ambient' where where B = B = -1.2815 -1.2815 (kg-0625) (kg-0625) + 0.0284+ 0.0284

Livor mortisLivor mortis

is the settling of the blood at the lowest point is the settling of the blood at the lowest point after death. Since the heart is no longer after death. Since the heart is no longer pumping, gravity causes the blood to pool at the pumping, gravity causes the blood to pool at the lowest point of the body. lowest point of the body.

At first, theses patches appear pink, however, At first, theses patches appear pink, however, with time the blood turns purplish blue Places in with time the blood turns purplish blue Places in the body where blood flow is constricted, such the body where blood flow is constricted, such as where is pressing against a hard surface, are as where is pressing against a hard surface, are not discolored. The process begins in as little as not discolored. The process begins in as little as 30 min but does not become permanent until 30 min but does not become permanent until about 8 h after death. A forensic pathologist can about 8 h after death. A forensic pathologist can use this informa tion to determine if the body use this informa tion to determine if the body has been moved after death and also to get has been moved after death and also to get some idea about the time of death (PMI).some idea about the time of death (PMI).

Rigor mortisRigor mortis is the stiffening is the stiffening of the muscles of the body.of the muscles of the body.

After death the muscles of the body After death the muscles of the body relax. Then they begin to contract relax. Then they begin to contract because of chemical changes.because of chemical changes.

Rigor mortis can be observed about 2 Rigor mortis can be observed about 2 h after death. It is usually detected in h after death. It is usually detected in the head first and then moves into the head first and then moves into the extremities. the extremities.

Rigor mortis is normally complete Rigor mortis is normally complete after 6 h and begins to leave the body after 6 h and begins to leave the body after 24 h. After 40 h the signs of after 24 h. After 40 h the signs of rigor mortis are completely grigor mortis are completely g

There are many factors that There are many factors that affect the timing of rigor mortis, affect the timing of rigor mortis, so it is not considered reliable so it is not considered reliable enough to determine the time of enough to determine the time of death but can be used to help death but can be used to help corroborate other methods.corroborate other methods.

The main tool a pathologist uses to The main tool a pathologist uses to determine the cause and man ner of a determine the cause and man ner of a suspicious death is an suspicious death is an autopsy,autopsy, The The word word autopsyautopsy comes from a Latin comes from a Latin expression meaning "seeing with your expression meaning "seeing with your own eyes."own eyes."

A A pathologistpathologist, with the help of an , with the help of an assistant called a assistant called a dienerdiener, performs the , performs the autopsy.autopsy.

AUTOPSYAUTOPSY

The whole procedure is carried out The whole procedure is carried out in a solemn and dignified manner. in a solemn and dignified manner. Autopsy suites often have the Autopsy suites often have the Latin inscrip tion Latin inscrip tion Hie locus est ubi Hie locus est ubi mors gaudet succurrere vitae, mors gaudet succurrere vitae,

which means "This is the place which means "This is the place where death rejoices to teach where death rejoices to teach those who live," posted on the those who live," posted on the wall.wall.

There is always a distinct smell There is always a distinct smell associated with an autopsy. associated with an autopsy.

It makes some people sick and some It makes some people sick and some faint. faint.

Many pathologists use a small dab of oil Many pathologists use a small dab of oil of wintergreen below their noses and of wintergreen below their noses and on their masks to help with the smell. on their masks to help with the smell.

The longer a person has been dead, the The longer a person has been dead, the more the oil of wintergreen is needed.more the oil of wintergreen is needed.

Autopsy ProcedureAutopsy Procedure

1.1. First the pathologist conducts a First the pathologist conducts a gross examination of the exterior of gross examination of the exterior of the body and the sheets or bag used the body and the sheets or bag used to cover and transport it.to cover and transport it.

2.2. Records are made of the decedent's Records are made of the decedent's name, height, weight, and visi ble name, height, weight, and visi ble characteristics. Photographs are characteristics. Photographs are taken from every possible angle. taken from every possible angle.

3.3. Ultraviolet lights are also used to Ultraviolet lights are also used to examine the body.examine the body.

4.4. Next, samples such as blood, Next, samples such as blood, urine, hair, and oral swabs are urine, hair, and oral swabs are taken. taken.

5.5. Scrapings from under the nails Scrapings from under the nails are also obtained. are also obtained.

6.6. The body is also x-rayed.The body is also x-rayed.7.7. The pathologist then makes a Y The pathologist then makes a Y

incision with a scalpel. Since the incision with a scalpel. Since the heart is not pumping, there is heart is not pumping, there is almost no bleeding. almost no bleeding.

8.8. Some pathologists make two Some pathologists make two shoulder-to-midchest incisions, and shoulder-to-midchest incisions, and others use one sweeping motion from others use one sweeping motion from one shoulder, under the nipples, to one shoulder, under the nipples, to the other shoulder.the other shoulder.

9.9. The Y is then extended from the The Y is then extended from the bottom of the Y at the midchest to bottom of the Y at the midchest to the pubic bone. the pubic bone.

10.10. An incision is also made across the An incision is also made across the skull from ear to ear. The skin is skull from ear to ear. The skin is pulled back and the bone cut with a pulled back and the bone cut with a vibrating saw.vibrating saw.

11.11. The pathologist removes the brain and The pathologist removes the brain and major organs (such as the heart, lungs, major organs (such as the heart, lungs, kidneys, liver, and spleen), which are kidneys, liver, and spleen), which are carefully exam ined and then weighed. carefully exam ined and then weighed. Small sections of the organs are routinely Small sections of the organs are routinely collected, and the samples are placed in collected, and the samples are placed in special jars for further analysis. These special jars for further analysis. These samples are usually sent to a histology lab samples are usually sent to a histology lab where they can be mounted as slides and where they can be mounted as slides and any abnormalities analyzed.any abnormalities analyzed.

12.12. The pathologist makes a detailed The pathologist makes a detailed investigation of the internal body and investigation of the internal body and examines the neck and windpipe for examines the neck and windpipe for possible abnormalities.possible abnormalities.

13.13.The pathologist makes a The pathologist makes a detailed investigation of the detailed investigation of the internal body and examines the internal body and examines the neck and windpipe for possible neck and windpipe for possible abnormalities.abnormalities.

14.14.Once the examination is Once the examination is complete, the pathologist puts complete, the pathologist puts the organs back into the body the organs back into the body

15.15.The body is then sewn back The body is then sewn back together.together.

forensic toxicologistforensic toxicologist

a person, normally with an advanced degree, a person, normally with an advanced degree, who detects the pres ence of poisons or drugs who detects the pres ence of poisons or drugs in body fluids, tissues, and organsin body fluids, tissues, and organs

is normally sent samples from a body is normally sent samples from a body whenever the cause of death is uncertain. The whenever the cause of death is uncertain. The presence of poisons or drugs, as well as the presence of poisons or drugs, as well as the quantities, is essential to the pathologist's quantities, is essential to the pathologist's determina tion of the cause of death.determina tion of the cause of death.

works with specialized instruments such as works with specialized instruments such as high-performance liquid chromatographs, gas high-performance liquid chromatographs, gas chromatographs, and mass spectrometers, chromatographs, and mass spectrometers, which can detect extremely minute quantities which can detect extremely minute quantities of toxic or illegal substances in the human of toxic or illegal substances in the human body.body.

odontologisodontologistt

is a forensic dentist who applies the is a forensic dentist who applies the science of dentistry to police science of dentistry to police investigations. investigations.

When a body has been severely When a body has been severely burned or disfigured, an burned or disfigured, an odontologist can still make a odontologist can still make a positive identification through dental positive identification through dental records. This is especially useful in records. This is especially useful in the case of a bombing or an airplane the case of a bombing or an airplane or train accident where there is a or train accident where there is a large number of victims and the large number of victims and the damage may preclude.damage may preclude.

In some cases an In some cases an odontologist can odontologist can match bite marksmatch bite marks to the teeth of a to the teeth of a suspect. These suspect. These can include bite can include bite marks on the skin marks on the skin and also those and also those left behind as an left behind as an impression on impression on some other some other material.material.

A forensic psychiatristA forensic psychiatrist

a medical doctor who specializes a medical doctor who specializes in application of psychiatry to in application of psychiatry to law. law.

Once a suspect is in custody, a Once a suspect is in custody, a foren- sic psychiatrist can testify foren- sic psychiatrist can testify whether the suspect is whether the suspect is competent to stand trial and is competent to stand trial and is responsible for their actionsresponsible for their actions

forensic engineerforensic engineer

applies engineering principles to applies engineering principles to law. They; often called into cases law. They; often called into cases when there is a structural failure when there is a structural failure such as bridge or building such as bridge or building collapse. The forensic engineer collapse. The forensic engineer can analyze the structure and can analyze the structure and determine the cause of the determine the cause of the failure..failure..

forensic entomologistforensic entomologist

applies the study of insects to applies the study of insects to law. One of the most common law. One of the most common insects used is the insects used is the blowflyblowfly..

A A blowflyblowfly almost always lays its eggs in almost always lays its eggs in dead tissue.dead tissue.

Certain varieties begin laying eggs Certain varieties begin laying eggs within minutes of death. Because of the within minutes of death. Because of the availability of moisture, blowfly eggs are availability of moisture, blowfly eggs are normally found in open wounds and in normally found in open wounds and in the head orifices (nose, ears, and the head orifices (nose, ears, and mouth). The eggs hatch and release mouth). The eggs hatch and release blowfly larvae (maggots), which continue blowfly larvae (maggots), which continue to feed on the body and grow and shed to feed on the body and grow and shed their skins. their skins.

The stages of development The stages of development that a blowflythat a blowfly

The third time they shed skin it forms The third time they shed skin it forms a hard capsule around them called a a hard capsule around them called a puparium. puparium.

Finally, the adult blowfly emerges Finally, the adult blowfly emerges from the puparium and after a day or from the puparium and after a day or two flies away. Evidence of the eggs, two flies away. Evidence of the eggs, larvae (maggots), puparia, and adult larvae (maggots), puparia, and adult flies can be collected from the body flies can be collected from the body and used to determine the time of and used to determine the time of death. death.

An accurate knowledge of the An accurate knowledge of the temperature and weather temperature and weather conditions is also needed since conditions is also needed since these greatly affect the timing of these greatly affect the timing of the life cycle of the blowfly. the life cycle of the blowfly. undergoesundergoes

Eggs------Eggs------> > Larvae (maggots)Larvae (maggots) > >

PupariumPuparium »• Adult fly»• Adult fly

forensic anthropologistforensic anthropologist

performs specialized examinations of performs specialized examinations of human skeletal remains or badly human skeletal remains or badly decomposed bodies for the pur pose decomposed bodies for the pur pose of identification. of identification.

A forensic anthropologist may be A forensic anthropologist may be asked to help determine the cause of asked to help determine the cause of death, sex, age, postmortem interval, death, sex, age, postmortem interval, and race.and race.

They are almost always called to help They are almost always called to help identify skeletal remains found when identify skeletal remains found when diggingdigging

ORGANIZATION:ORGANIZATION:

Crime laboratories in the United Crime laboratories in the United States are run at two levels:States are run at two levels:

1) There are federal crimes labs 1) There are federal crimes labs run by the U.S. government run by the U.S. government

2)each state has its own crime 2)each state has its own crime labs that are normally operated labs that are normally operated under laboratories that carry out under laboratories that carry out analyses for a fee.analyses for a fee.

The five main federal labs The five main federal labs are theare the

1.1. ..Department of Justice (DOS) Department of Justice (DOS) laboratories at the laboratories at the Federal Bureau of Federal Bureau of Investigation (FBI)Investigation (FBI)

2.2. the the United United States States Secret Service Secret Service (USSS),(USSS),

3.3. the the Department of the Treasury Department of the Treasury labs labs at the at the Drug Enforcement Adminis Drug Enforcement Adminis tration (DEA) tration (DEA)

4.4. tthe he Bureau of Alcohol, Tobacco, and Bureau of Alcohol, Tobacco, and Firearms Firearms (ATF), (ATF),

5.5. postal Inspection Services (PIS) at postal Inspection Services (PIS) at the U. S. Postal Service (USPS).the U. S. Postal Service (USPS).

The main forensic laboratory in The main forensic laboratory in the United States is run by the the United States is run by the FBI and was created on FBI and was created on November 24,1932. November 24,1932. J. Edgar J. Edgar HooverHoover established the FBI as established the FBI as the central forensic laboratory the central forensic laboratory for the United States. for the United States.

Along with finger prints, many Along with finger prints, many other types of forensic standards other types of forensic standards are kept at the FBI lab. are kept at the FBI lab. Comparison standards for paint Comparison standards for paint samples, tire patterns, DNA, samples, tire patterns, DNA, bullets, explosives, and fibers bullets, explosives, and fibers are but a few of the resources are but a few of the resources available from the FBI.available from the FBI.

UNITSUNITS

Because of the need for Because of the need for specialization, forensic labs are specialization, forensic labs are normally separated into normally separated into functional units by scientific functional units by scientific discipline. Most crime labs have discipline. Most crime labs have the following sections.the following sections.

ChemistryChemistry

The chemistry unitThe chemistry unit is often the largest is often the largest unit in the modern crime lab. unit in the modern crime lab.

This unit possesses some of the most This unit possesses some of the most sophisticated and expensive sophisticated and expensive equipment in the crime lab, such as a equipment in the crime lab, such as a gas chromatograph-mass gas chromatograph-mass spectrometer, which is used in spectrometer, which is used in analyzing for drugs.analyzing for drugs.

Since the major ity of the evidence Since the major ity of the evidence submitted to the crime lab is drug-submitted to the crime lab is drug-related, this unit is normally the related, this unit is normally the largest and has the most personnel.largest and has the most personnel.

The Sixth Amendment guarantees the right The Sixth Amendment guarantees the right of the accused to a speedy trial.of the accused to a speedy trial.

For this reason the evidence from an arrest For this reason the evidence from an arrest involving drugs must be analyzed by the involving drugs must be analyzed by the chemistry unit in a timely manner and chemistry unit in a timely manner and submitted to the courts. submitted to the courts.

The chemistry unit also has other The chemistry unit also has other instrumentation that is used for the instrumentation that is used for the analysis of trace evidence, explosives, analysis of trace evidence, explosives, metals, paints, and minerals.metals, paints, and minerals.

PhysicsPhysics

The physics unit The physics unit is often involved in is often involved in the reconstruction of crime scenes. the reconstruction of crime scenes. Through the use of Newton's laws of Through the use of Newton's laws of motion and the lawmotion and the law

Of conservation of energy a forensic Of conservation of energy a forensic physicist can reconstruct a car physicist can reconstruct a car accident to determine what happened accident to determine what happened and who was at fault. Laser can be and who was at fault. Laser can be used to reconstruct a shooting to used to reconstruct a shooting to determine who fired which bullet.determine who fired which bullet.

BiosciencesBiosciences

The The biosciences unitbiosciences unit is staffed by is staffed by specially trained biologists who specially trained biologists who analyze biological materials for analyze biological materials for DNA. The evidence can include DNA. The evidence can include blood, semen, saliva, skin, hair, blood, semen, saliva, skin, hair, and other samples, which can be and other samples, which can be positively linked to a person by positively linked to a person by the DNA information contained the DNA information contained in each cell.in each cell.

ToxicologyToxicology

It is the function of the It is the function of the toxicology unit to analyze body toxicology unit to analyze body fluids, tis sues, and organs for fluids, tis sues, and organs for the presence of drugs or the presence of drugs or poisons. Samples are routinely poisons. Samples are routinely sent to this unit by a medical sent to this unit by a medical examiner as part of an autopsy.examiner as part of an autopsy.

FirearmsFirearms

The firearms unit test-fires suspect The firearms unit test-fires suspect weapons into a bullet recovery tank weapons into a bullet recovery tank so that by using a comparison so that by using a comparison microscope one can link a bullet to a microscope one can link a bullet to a crime scene. crime scene.

A comparison microscope can also be A comparison microscope can also be used to match markings left on used to match markings left on cartridge cases by the firing pin, cartridge cases by the firing pin, breech block, extractor, or ejector of breech block, extractor, or ejector of the weapon.the weapon.

The fingerprints unit can uncover The fingerprints unit can uncover prints that are invisible to the naked prints that are invisible to the naked eye (latent prints). eye (latent prints).

This can be accomplished by dusting, This can be accomplished by dusting, chemical, ultraviolet, and alternate chemical, ultraviolet, and alternate light techniques. light techniques.

The prints can be manually classified The prints can be manually classified or scanned into an automated or scanned into an automated fingerprint identification system.fingerprint identification system.

PhotographyPhotography

The photography unit has film and The photography unit has film and digital cameras to record the crime digital cameras to record the crime scene. Infrared photography is also scene. Infrared photography is also used in the study of ques tioned used in the study of ques tioned documents and bloodstained garments.documents and bloodstained garments.

The photography unit has film and The photography unit has film and digital cameras to record the crime digital cameras to record the crime scene. Infrared photography is also scene. Infrared photography is also used in the study of ques tioned used in the study of ques tioned documents and bloodstained garments. documents and bloodstained garments.

Questioned DocumentsQuestioned Documents

““Any document suspected of Any document suspected of being forged, altered, or being forged, altered, or counterfeit is sent to the counterfeit is sent to the questioned documents unit.questioned documents unit.

EVIDENCE COLLECTIONEVIDENCE COLLECTION::

Many larger crime labs have a Many larger crime labs have a specialized evidence collection specialized evidence collection unit. These vans contain all the unit. These vans contain all the devices needed to properly devices needed to properly collect different types of collect different types of evidence from a crime scene that evidence from a crime scene that might otherwise be missed.might otherwise be missed.

EVIDENCE SUBMISSION AND EVIDENCE SUBMISSION AND HOLDINGHOLDING

Evidence taken to the crime lab by Evidence taken to the crime lab by crime scene investigators is crime scene investigators is logged in by the evidence logged in by the evidence submission unit. This unit submission unit. This unit maintains the legal chain of maintains the legal chain of custody and is where the evidence custody and is where the evidence submission form is delivered.submission form is delivered.

Read the OJ Simpson info from notesRead the OJ Simpson info from notes

Types of Evidence

“You can learn a lot by just watching.”

—Yogi Berra, former New York

Yankees catcher and sage

Chapter 2

Types of Evidence

Two general types: Testimonial—a statement made under oath; also

known as direct evidence or Prima Facie evidence

Physical—any object or material that is relevant in a crime; also known as indirect evidence. Examples are hair, fiber, fingerprints, documents, blood, soil, drugs, tool marks, impressions, glass.

Chapter 2

Reliability of EyewitnessFactors:

Nature of the offense and the situation in which the crime is observed

Characteristics of the witness Manner in which the information is retrieved

Additional factors: Witness’s prior relationship with the accused Length of time between the offense and the

identification Any prior identification or failure to identify the

defendant Any prior identification of a person other than the

defendant by the eyewitness

Chapter 2

Eyewitness

A police composite may be developed from the witness testimony by a computer program or forensic artist.

“Perception is reality.”

As a result of the influences in eyewitness memory, physical evidence becomes critical. Faces—a composite program

by InterQuest

Chapter 2

Value of Physical Evidence

Generally more reliable than testimonial Can prove that a crime has been committed Can corroborate or refute testimony Can link a suspect with a victim or with a crime

scene Can establish the identity of persons associated

with a crime Can allow reconstruction of events of a crime

Chapter 2

Reconstruction

Physical Evidence is used to answer questions about:

what took place how the victim was killed number of people involved sequence of events

A forensic scientist will compare the questioned or unknown sample with a sample of known origin.

Chapter 2

Types of Physical Evidence

Transient Evidence—temporary; easily changed or lost; usually observed by the first officer at the scene

Pattern Evidence—produced by direct contact between a person and an object or between two objects

Conditional Evidence—produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event

Transfer Evidence—produced by contact between person(s) or object(s), or between person(s) and person(s)

Associative Evidence—items that may associate a victim or suspect with a scene or each other; ie, personal belongings

—Lee and Labriola in Famous Cases, 2001

Chapter 2

Examples of Transient Evidence

Odor—putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke

Temperature—surroundings, car hood, coffee, water in a bathtub, cadaver

Imprints and indentations—footprints, teeth marks in perishable foods, tire marks on certain surfaces

Markings

Chapter 2

Examples of Pattern Evidence

Pattern Evidence—most are in the form of imprints, indentations, striations, markings, fractures or deposits.

Clothing or article distribution

Gun powder residue Material damage Body position Tool marks Modus operandi

Blood spatter Glass fracture Fire burn pattern Furniture position Projectile trajectory Tire marks or skid marks

Chapter 2

Examples of Conditional Evidence

Light—headlight, lighting conditions

Smoke—color, direction of travel, density, odor

Fire—color and direction of the flames, speed of spread, temperature and condition of fire

Location—of injuries or wounds, of bloodstains, of the victim’s vehicle, of weapons or cartridge cases, of broken glass

Vehicles—doors locked or unlocked, windows opened or closed, radio off or on (station), odometer mileage

Body—position, types of wounds; rigor, livor and algor mortis

Scene—condition of furniture, doors and windows, any disturbance or signs of a struggle

Chapter 2

Classification ofEvidence by Nature

Biological—blood, semen, saliva, sweat, tears, hair, bone, tissues, urine, feces, animal material, insects, bacterial, fungal, botanical

Chemical—fibers, glass, soil, gunpowder, metal, mineral, narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants, fertilizer

Physical—fingerprints, footprints, shoe prints, handwriting, firearms, tire marks, tool marks, typewriting

Miscellaneous—laundry marks, voice analysis, polygraph, photography, stress evaluation, psycholinguistic analysis, vehicle identification

Chapter 2

Evidence Characteristics

Class—common to a group of objects or persons

Individual—can be identified with a particular person or a single source

Blood DNA TypingFingerprints

Chapter 2

Class vs Individual Evidence

Which examples do you think could be individual evidence?

Chapter 2

Class vs Individual Evidence

The large piece of glass fits to the bottle—it is individual evidence

These fibers are class evidence—there are millions like them.