FORESNSIC UNIT 1: EVIDENCE COLLECTION

BALLISTICS: GUNS/BULLETS

-Bullets and cartridge's casings are collected with tweezers and are placed into a small bag or box

-Bullets and magazines are removed from the gun and placed into their own evidence bag

-The gun is collected into a special gun box that secures the trigger and prevents it from firing

ARSON

-Fabrics and materials are collected from the scene and are tested chemically in the lab for traces of accelerant that can indicate arson

-Evidence is collected into a sealed glass or metal container to prevent evaporation

FOOTWEAR IMPRESSIONS

-Footwear and tread print impressions and be 3D (in snow or mud) or 2D (in blood or dust)

-Casts are made of any 3D impression, special casting material is poured over the print, hardened then collected

BODILY FLUIDS

-Semen, saliva, blood

-Items with fluids are put into a porous (paper) bag and are allowed to dry completely, if damp, and sealed in a plastic as if not bacteria may destroy the evidence in the fluid

-If a bloody item is unable to be collected (wall, floor) it will be dabbed with a sterile cotton swab and put into a porous bag

TRACE EVIDENCE

-Hair, paint chips, fiber, soil, and shards of glass for ex)

-Trace evidence is collected with tweezers and placed into a paper bindle which then goes into a evidence bag

-Any fragile objects are placed into a appropriate sized rigid container to prevent breaking

FINGERPRINTS

-CSI use fingerprint powder and a brush to find prints at a crime scene

-Different powders may be used depending on the material the print is on

-When a print is dusted, tape is applied over the print to collect it and then the tape is placed on a fingerprint card

TOOLMARK IMPRESSIONS

-Marks are FIRST photographed

-If the object is small enough the whole thing is collected

-If the object is big like a door, silicone is applied to the mark and makes a 3D cast of the impression

TOOLS

-The working end of the tool is wrapped in a clean cloth to protect it from damage or loss of trace evidence and then the tools are placed in rigid cardboard boxes

FOOTWEAR

-Shoes are placed into a plastic bag/box and taken to the lab

-Black ink is applied to the sole of the shoe and used to make a impression on paper

DOCUMENTS

-Collected in a plastic bag or cellophane envelope

-Documents are examined for

-Type of paper/ink used

-Fingerprints or DNA left on paper

-Unique characteristics of handwriting or type font

HAIR

-Hair can indicate what animal it is from

-If hair is human it can give clues to their ethnicity

-Hair can hold a record of poisons and drugs the person may be exposed to over months or years

What can hair and trace evidence demonstrate

-Hair and trace evidence can demonstrate the LOCARD EXHCHANGE PRINCIPLE, where there is contact between two items (ex. cat and glove, there will be an exchange of material as the cat hair will stick to the glove)