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

Forensic Forensic ScienceScience

Forensic means connected with the courtroom.

It’s the application of science to law. One of the types of Analytical Chemistry.

““Every contact leaves a Every contact leaves a trace.” -Edmond Locardtrace.” -Edmond Locard

Every criminal leaves something

at the scene of a crime and

carries something away.

At the Scene of the At the Scene of the CrimeCrime

It is vital that a crime scene be sealed off to preserve any evidential trace.

Who might disturb the scene?

Investigating OfficerInvestigating Officer

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

Search TeamSearch 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 InvestigationInitial 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 Two Kinds of Evidential MaterialMaterial

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 Chain of CustodyCustody

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 TrialThe OJ Simpson Trial

Irrefutable Forensic Evidence Irrefutable Forensic Evidence include: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 Examples of Mishandled Evidence:Mishandled Evidence:

Police kept victims bodies lying open more than ten hours before examiners was allowed at scene.

Example of Example of Mishandled Mishandled

Evidence: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.

AutopsyAutopsy

Autopsy means seeing for oneself It is the task of examining a dead

body in detail, and determining the cause of death.

FirstFirst

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 DeathTime of Death

Why is it important to determine time of death?

The suspects’ alibis can be validated or proven false.

Ways to Determine Ways to Determine the Time of Deaththe Time of Death

1) Temperature2) Body Fluids3) Rigor Mortis

TemperatureTemperature

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 FluidsBody 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 MortisRigor 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 AutopsyDuring 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?Unknown Victims?

Can use the following to determine the identity of the victim:

FingerprintsCredit cards, drivers license, bills,

ticket stubs.Shoe castsTeeth casts

Internal Autopsy Internal Autopsy InvestigationInvestigation

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.