Forensic Science Forensic means connected with the courtroom. It’s the application of science to law. One of the types of Analytical Chemistry.

“ Every “ Every contact leaves a trace.” -Edmond Locard Every criminal leaves something at the scene of a crime and carries something away.

At the Scene of the Crime It is vital that a crime scene be sealed off to preserve any evidential trace. Who might disturb the scene?

Investigating Officer Should not touch anything until search team arrives. Make observations…. They must keep their eyes open, mouth shut, hands in pockets.

Search Team They look for something that should not be there. Such as: shoeprints, signs of struggle, tracks from a car tire, paint flecks, fibers from torn clothing, weapon, blood, bullets, etc.

Initial Investigation Collect each physical object (with gloves or forceps) and put in plastic bag or box. Label with full details of time, location and position it was found. Photographs are required. Hands and feet of dead person enclosed in plastic or paper bag before removing the body. Why??

Fingerprints, bloodstains scraped for later analysis, dust and fibers collected by miniature vacuum, documents, and ashes can also be collected.

Two Kinds of Evidential Material 1) Individual and Unique Example: tool marks, bullets, or fingerprints 2) Identifiable but not Unique Example: fibers from piece of clothing, fragments, paint or glass etc.

Chain of Custody Different items of evidence pass from hand to hand (officer to officer to various laboratory examiners) Each move must be logged and signed for. Evidence is not as valid if this is not done.

The OJ Simpson Trial

Irrefutable Forensic Evidence include: : Blood splashes at scene matching OJ’s blood. A pair of socks soaked in victims blood found at foot of his bed. Blood stained glove found behind OJ’s house matching one at the scene.

Examples of Mishandled Evidence: Police kept victims bodies lying open more than ten hours before examiners was allowed at scene.

Example of Mishandled Evidence: Sample of blood taken from OJ decreased in volume while in police custody=planted evidence? Bloody socks were not handled correctly. Gloves were too tight for OJ’s hands.

Autopsy Autopsy means seeing for oneself It is the task of examining a dead body in detail, and determining the cause of death.

First Examiner must determine the victim is definitely dead. Cases of drug overdoses, poisoning, or electrocution can induce a state of “suspended animation:” there is no discernible heartbeat or respiration. The victim may be revived in the intensive care unit.

Time of Death Why is it important to determine time of death? The suspects’ alibis can be validated or proven false.

Ways to Determine the Time of Death 1) Temperature 2) Body Fluids 3) Rigor Mortis

Temperature The body begins to loose heat from the moment of death. Unclothed bodies cool quicker and fatter bodies cool less rapidly. In hot climates there may be no cooling at all – body may become WARMER after death. People who die from hypothermia begin cooling at a lower temperature.

Body Fluids Blood, urine, and the liquid that surrounds the brain. Changes in these fluids provide indication of time of death. Analysis of the Potassium inside of vitreous humour of the eye. It increases after death. A problem: There is no way of allowing for physical or emotional conditions affecting rate of change.

Rigor Mortis Stiffening of the muscles after death. Muscles of the face begin to stiffen within 1-4 hours and limbs 4-6 hours. After 12 hours the body is rigid & then gradually relaxes as tissue decomposition sets in. Extreme emotion or violence may cause rigor mortis to set in immediately after death.

During Autopsy Pathologist talks through every stage of examination. First observes the outward appearance: physical features, race, clothing, color of body. Checks any wounds and the condition of the eye. Is there Hypostasis- dark patches or any injection, weapon marks.

Unknown Victims? Can use the following to determine the identity of the victim: Fingerprints Credit cards, drivers license, bills, ticket stubs. Shoe casts Teeth casts

Internal Autopsy Investigation Swab specimens to check for foreign donor. Make a Y-shaped incision behind each ear and down the sternum (this allows you to peel back skin). Cut through Sternum to remove lungs, heart, and other organs. Use a saw to cut open skull and pull top off. Examine brain and inside skull. Check air passages (determine if drowned or in a fire). Check Stomach contents to predict time elapsed between last meal and time of death.