forensic science - … · forensic science -debatable ... 1- state the problem 2-form a hypothesis...
TRANSCRIPT
Forensic Science
-Debatable
-Is the application of science to those
criminal and civil laws that are enforced
by police agencies in a criminal justice
system.
Important People Mathieu Orfila (1787-1853)-Father of forensic toxicology
-Spanish
-Taught medicine in France
-1814-published a report on the detection of poisons and their effects on animals.
Alphonse Bertillon (1853-1914)-Father of original identification.
-Developed the science of anthropometry-a systematic procedure of taking a series of body measurements as a means of distinguishing an individual from another.
-Replaced by fingerprinting.
Francis Galton (1822-1911) -1st definite study of fingerprints and developed a methodology of classifying them for filing.
-1892-Wrote book on fingerprinting.
Important People Cont.
Leone Lattes (1887-1954) -Discovered the ABO blood typing
-1915-Developed a procedure to determine blood group of dried blood.
Calvin Goddard (1891-1955)-U.S. Army Colonel
-Began the use of comparison microscope to match fired and test fired bullets from a gun--Ballistics
Albert S. Osborn (1858-1946) -Wrote questioned documents (1910)
-Developed the fundamental principles of document examination which was accepted by the courts.
Important People Cont.
Hans Gross (1847-1915)-Prosecutor and judge in Australia
-Spent years developing and studying the principles behind a criminal investigation.
-Incorporated fields of microscopy , chemistry, physics, minerology, zoology, botany, and fingerprinting.
Edmond Locard (1877-1966)
-French
-Developed the “Locard’s Principle”
“With every contact people have, they leave something behind.”
The Scientific Method and The Criminal Investigation
Scientific Method
1- State the problem 2-Form a hypothesis 3-Collect data Observing and
experimenting 4-Interpret the data 5-If data supports
hypothesis, collect more data
6-Draw conclusions
Criminal Investigation -What crime was committed and in what
jurisdiction? -Hypothesize as to possible suspects based
on information gathered from witnesses, physical evidence at the crime scene, and motive (if determined)
-Seek out pertinent records -Review and evaluate the evidence so far
available relative of making a case-for or against each suspect
-Seek additional evidence that will help support and prove your case
-Arrest suspect and continue seeking evidence to support or refute the guilt of defendant
The answer is always there, it is just a matter of asking the right questions.
Crime Scene Physical Evidence: Only and all objects that can establish that a crime has been
committed or can provide a link between a crime and its victim or a crime and its perpetrator.
Types of Evidence
Temporary Conditional Associative Pattern Trace/Transfer -May be -Associated -Links the -Blood -Produced by changed or with specific suspect or -Impressions physical contact can be lost. conditions at victim to the -Tire treads with some surface. the crime scene. scene. -Residues that show the Modus Operandi (how it occurred)
Crime Scene Cont.
Common Examples of Evidence
-Bullets or Firearms -Glass -Fingerprints: visible or latent -Organs -Hair -Paint -Blood, Semen, Saliva -Plastic Bags -Footprints (impressions) -Plastic, Rubber, or other polymers -Documents -Powder Residue (gun) -Drugs -Soil and Minerals
-Explosives -Tool Markings
-Petroleum Products -Vegetative (wood, plants, etc…)
-Serial Numbers
-Fiber: Natural or Synthetic
Crime Scene Cont.
Class Evidence -Evidence that posses
characteristics that can only be associated with as group and never a single source.
Ex) Blood Types
Individual Evidence
-Evidence that can be associated with a common source with extremely high degree of probability
Processing The Scene
Secure and Isolate the Crime Scene -1st officer on the scene -Goal is to preserve and protect to the greatest extent -Only allow authorized people in -Rope and barracades Record the Scene -Limited amount of time at the scene only one shot to find everything. -Don’t want to touch anything. -Photograph the scene scale. -Sketch the scene rough and then final. -Take notes.
Processing The Scene Cont.
Conduct a Systematic Search for Evidence -A search for physical evidence at a crime scene must be thorough and systematic: Spiral Strip or Line Grid Quadrant (Zone)
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Processing The Scene Cont.
Collect and Package Physical Evidence: -The integrity of the evidence is best maintained when the item is kept in its original
condition. -Do this to prevent contamination, breakage, evaporation, accidental damage, or loss. -Each piece will have its own container/bag. Maintain Chain of Custody: -The documentation on the container that shows who is and where the evidence went
from the crime scene to the court house. Obtain Controls: -This is used to match evidence from the scene to an individual or known object. Submit Evidence to the Laboratory: -There are different laboratories under different jurisdictions. Depending on the
investigators and type of crime depends where the evidence was sent.
Processing The Scene Cont.
Henry Lee’s Linkage Principle: Crime Scene Victim Evidence Suspect *You need to be able to argue the case between all four “Air Tight Case”
Product Rule:
-The probability of independent events.
Crime Scene Documentation
-The documentation of a crime scene consists of photographs helps document the facts and physical evidence at the crime scene.
-The crime scene sketch used to plot accurate measurements made at the scene.
-Taking notes Keep a log that records time of discovery of the crime.
Fixed Point Method
Bookshelf
-Door -Window -Wall Corner -Permanent Object -Pick two fixed points -Draw a line from the point to the object.