FSC239Y5 Lecture Notes - Lecture 1: Flashlight, Coroner, Electrostatic Generator
FSC239
1. Lecture 1: Crime Scene Investigation
Locard’s Principle
1. Every contact leaves a trace.
2. Suspect will leave something at the scene.
3. Suspect will take something away.
What evidence do we look for?
4. Fingerprints: Impressions from the friction ridges on our fingers.
1. They are reliable and persistent (remain the same). They are formed during the
second trimester of pregnancy and do not change until decomposition after
death.
2. They are unique. No two people have the same fingerprints (identical twins have
same DNA but different fingerprints).
3. Best surfaces to find fingerprints are firm and smooth, also paper.
4. Methods: Brush and powder, glue fuming (adheres to fingerprint) and laser
(spreads beam onto glue with dye), and chemical treatment.
5. When finding fingerprints you first write your initials and give it an R number
(first fingerprint is R1, second if R2, and so on). Next you photograph the
fingerprints (in case you mess up lifting with tape and also to prove to the court
that you found the fingerprint, where it was found, etc). Next identify the
fingerprint through computer data base.
5. Footwear:
1. Ambient light on footprint (not visible) vs. Oblique light on footprint (visible).
2. Footwear could be lifted with an electrostatic machine.
3. Two types of characteristics:
1. Classic: Size, shape, shoe pattern.
2. Unique/Accidental: Different wear patterns, different materials in the
bottom of the shoes.
6. Blood and Trace Evidence
1. Several footwear impressions could be in the blood (can only be photographed).
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Locard"s principle: every contact leaves a trace, suspect will leave something at the scene, suspect will take something away. What evidence do we look for: fingerprints: impressions from the friction ridges on our fingers, they are reliable and persistent (remain the same). They are formed during the second trimester of pregnancy and do not change until decomposition after death: they are unique. Next you photograph the fingerprints (in case you mess up lifting with tape and also to prove to the court that you found the fingerprint, where it was found, etc). Steps to follow: once entering the scene, bring flashlight and examine any foot prints with the oblique light (essential). Try not to walk around and contaminate the scene with your footprints (contain): when you take photos and notes of everything you can always go back knowing where, when, etc, walk through access.
