death. do now: brainstorm some observations a forensic scientist can look for in order to determine...

Do Now: Brainstorm some observations a forensic scientist can look for in order to determine the time of death of a victim.

Read “Worms Crawl In” and answer the questions. Hand in your answers.

Closure: How can insects be used to determine time of death?

Objectives: Discover information that can be found about the time of death at a crime

scene.

Do Now: What does “death” mean to you?

Objectives: Differentiate between, meaning manner and cause of death

Meaning of Death

End of life

“irreversible cessation of circulation of blood”

Brain activity stopped


Forensic PathologistConducts autopsy (post-mortem)

Medical doctor who conducts examination on deceased to determine manner and cause of death

Medical examiner (M.E.), coroner


Manner of Death: Means by which they died

NaturalAccidentalSuicidalHomicidal Undetermined


Cause of Death: Reason they died

Ex. Natural

Heart attack

Stroke

Respiratory failure

Ex. Homicide/Suicide

Hanging

Drowning

Asphyxiation

Poison


Gunshot wound

Stippling (powder burns) indicating gun was a few inches away

Starring indicating barrel touching skin


Strangulation

Petechial hemorrhage as a result of strangulation


Mechanism of death: is the specific change in the body that brought about the end of life

Cause Mechanism

Shooting Loss of blood


Complete the death scenario reading and activity.

Closure: What manner of death would be the least helpful in solving a case?


Do Now: What is rigor mortis?

Objectives: Determine time of death using rigor mortis

Time of Death: When they died

Examples:

Livor Mortis

Rigor Mortis

Algor Mortis

Stomach and intestinal contents

Changes of the eye

Stages of decomposition

Insects (forensic entomology)


Livor Mortis: pooling of blood in tissues after death (lividity)

Can determine if body was moved

Begins 1-2 hrs. after death

2-8 hrs.: color disappears when skin is pressed

>8 hrs.: permanent discoloration


Factors affecting Livor Mortis

Hot day/area– blood pools faster

Cool day/area: slower process


Rigor Mortis: stiffening of skeletal muscles after death

Cause: no oxygen to cells calcium buildup muscle fibers remain contracted

Starts 1-2 hrs. after death

Starts at head legs

12 hrs: most rigid

Stiffness disappears after 24-48 hrs.


Factors affecting rigor mortis:Ambient temperature

Person’s weight

Type of clothing

Illness

Level of physical activity shortly before death

Sun exposure


Complete time of death using rigor mortis lab.

Closure: Explain the difference between livor mortis and rigor mortis.


Do Now: What can temperature of a body tell you the time of death?

Finish your rigor mortis worksheet and hand it in. You have 20 minutes.

Objectives: Determine time of death using algor mortis

Algor Mortis: cooling of body after death

Temperature loss in a corpse

Thermometer inserted in liver

1 hr. after death: cools 1.4°F per hour

After 1st 12 hrs: cools 0.7°F per hour until it reaches surrounding temp.

Objectives: Determine time of death using algor and rigor mortis

Factors affecting algor mortis:

Cooler environment – lose heat faster

Windy – fast heat loss

Excess body fat – slows heat loss

Clothing – slows heat loss

Rule of thumb: 1°F per hour


Stomach and Intestinal Contents

0-2 hours after last meal: undigested stomach contents present

4-6 hours after meal: stomach empty, food in S.I.

12+ hours after meal: S.I. empty, wastes in L.I.


Eye after death

Thin film on eye surface:

2-3 hours (eyes open)24 hours (eyes closed)


Start determining time of death using Algor mortis lab

Closure: Why is this lab just “estimating” time of death? (Why is it hard to pinpoint a specific TOD using algor mortis?)

Objectives: Determine time of death using rigor and algor mortis

Do Now: How many degrees Fahrenheit are lost from a dead body every hour for the first 12 hours?

Finish the Algor Mortis lab and hand it in.

Closure: Why does the rate of heat loss decrease after the first 12 hours?

Objectives: Determine time of death using algor mortis

Do Now: What is entymology? (Hint: entomon is Greek for insect)

Objectives: Determine time of death using insects (etymology)

Flies and maggots also provide an approximate time of death, very useful for cases where the body has been long dead.

Only certain insects will feed and lay eggs on a dead corpse and forensic entomologists study these insects, their larvae cycles and thereafter can determine whether a body has been dead for just one day or up to 3 or 4 weeks.

Forensic Entymology: study of insects in criminal investigations


Time Physical Appearance of Body Insects Present at that Stage0-3 days

Proteins and carbohydrates in the Blowflies e.g. Bluebottle

flies, Syrphidae flies deceased body begin to break down.

4-7 days

Body is starting to decay and causes the Fly larvae and beetle e.g. Rove

Beetles abdomen to inflate because of the gasesinside.

8-18 days

Decay is well and truly setting in; the Ants, cockroaches,

beetles and flies abdomen wall begins to break down.

19-30 days

The decaying body enters a stage know Beetles and mites e.g. Springtail beetle, Acari, as 'post-decay'; in wet, humid conditions, Nematocera (present only during the winter months), the body is sticky and wet; in hot dry Brachycera conditions, the body is dried out .

31 and over daysThe bones, skin and hair that remain no longer give off a powerful stench and smell just like the soil surrounding it.

Stages of Decomposition0-2 Days:

Green, purplish stainsSkin: marbled appearanceFace discoloredFlies lay eggs on corpse


http://www.deathonline.net/decomposition/decomposition/initial_decay_a.htm

4 Days:Skin blistersAbdomen swells (CO2 gas released by bacteria in intestines)Maggots on corpse


http://www.deathonline.net/decomposition/decomposition/putrefaction_a.htm

6-10 Days:Corpse bloats with CO2, chest and abdomen burst and collapseFluids leaks from body openingsEyeballs and other tissues liquifySkin sloughs offMore eggs, maggots, flies, beetles


http://www.deathonline.net/decomposition/decomposition/black_putrefaction_a.htm

10-20 Days:Bloated body collapsesFlattened body, creamy fleshStrong smell of decayFluids drain and seep

50-365 Days:– Body dry; decays

slowly– Hair disappears,

leaving bones


http://www.deathonline.net/decomposition/decomposition/butyric_fermentation_a.htm

http://www.deathonline.net/decomposition/decomposition/dry_decay_a.htm

Time lapse video of pig decaying

http://www.youtube.com/watch?v=yN8S6viF3Lw






Complete the insects reading

Closure: A body is found at the end stages of bloating. His skin is milky and there is a distinct odor of rotting flesh. Estimate how long the body has been there.


Do now: What does a forensic pathologist do?

Look over the autopsy and answer the following questions. Hand it in.

Closure: Is it possible that a person has no signs of rigor mortis but the insects found inside include eggs, larve, and pupa?

Objectives: Determine time of death using algor mortis, rigor mortis, livor

mortis, and insects.

Do now: which of the factors used to determine TOD do you think is the least accurate? Why?



Complete the “How did she die” lab and hand it in.

Recall food travels from the stomach small intestine large intestine.

ATP is the cells energy used to contract and relax muscles.

Normal body temperature 37C. Body heat stays at that temperature due to the circulatory system.

Closure: Why is it essential to test all 4 factors to determine the time of death?



Do now: Name three things that can slow down the rate of decomposition of a body.

Finish “When did she die” and hand it in.

Complete the estimating time of death worksheet and hand it in.

http://www.youtube.com/watch?v=AYrBgqojBKQ

Closure: Where is the temperature taken from in a dead body? (What body part?)





Do Now: What do pathologists look for in the external autopsy?

Watch the video and tell me :three ways corpses are usedWhy type of body parts can be transplanted?Would you donate your body to science and why?

Closure: Name some body systems examined in the internal autopsy.



Do Now: What concepts from DNA or TOD do you need help on?

Complete the Unit 1 and 2 review worksheet.

Closure: What concept(s) do you still have to study the most for tomorrow’s exam?


mortis, and insects. Review DNA

Do Now: What insect is the first to inhabit a cadaver?

Start the entymology (insects) lab. Try to get all measurements done today. We can take time for the questions tomorrow.

Closure: How can the size of an insect tell you an approximate TOD?

Objectives: Determine time of death using insects.

Do Now: Why can various sizes of the same insect be found in the body?

Complete the entymology (insects) lab and hand in.

Start test corrections and hand in by tomorrow.

Closure: How did you prepare for this test and will you prepare more in the future? If so, what will you do to prepare?

Objectives: Determine time of death using insects.

Do Now: Why do pathologist perform autopsies?

Watch the video and summarize some of his strange cases.

Closure: What was the most interesting autopsy he told you about?

Hand in your video answers and your do now sheets.

Objectives: Investigate the uses of autopsies.

death. do now: brainstorm some observations a forensic scientist can look for in order to determine...

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