Evidence Collection

What evidence? What types of evidence should be collected at a crime scene? What types of evidence should be collected at a crime scene? –Any physical evidence: blood, bodily fluids, hair, fibers, glass, paint, flammable liquids (in cases of arson), firearms, tool marks, fingerprints

Collecting blood Wet blood should be picked up using sterile gauze pads Wet blood should be picked up using sterile gauze pads Allow to air dry and then refrigerate or put in freezer (to prevent Allow to air dry and then refrigerate or put in freezer (to preventdenaturing) Do NOT dry in direct Do NOT dry in direct sunlight; do NOT heat blood

Collecting blood For dried blood, package material (sheet, shirt, clothing, etc.) in brown paper bag For dried blood, package material (sheet, shirt, clothing, etc.) in brown paper bag Place each separate stain in its own bag Place each separate stain in its own bag Do not use moistened cloth or paper to clean stains Do not use moistened cloth or paper to clean stains

Bodily fluids Semen, saliva, urine Semen, saliva, urine Allow to air dry, then package in separate brown paper bags Allow to air dry, then package in separate brown paper bags Follow same standards as for blood Follow same standards as for blood

Hair and fibers Pick up with fingers or tweezers Pick up with fingers or tweezers Place in paper bindle or coin envelope Place in paper bindle or coin envelope Can be picked up using tape, but only if it is allowed by the laboratory operating in your area Can be picked up using tape, but only if it is allowed by the laboratory operating in your area

Paint samples More useful if you have several layers in the paint sample More useful if you have several layers in the paint sample Use a clean knife blade to carefully scrape or flake the paint sample off Use a clean knife blade to carefully scrape or flake the paint sample off Place samples in Place samples in paper bindles, then in small envelopes

Flammable Liquids (arson) Check everywhere…mattresses, rugs, upholstery, walls, wood Check everywhere…mattresses, rugs, upholstery, walls, wood If liquids are in open containers, pour some into a glass vial and secure to make it airtight If liquids are in open containers, pour some into a glass vial and secure to make it airtight Soil, wood, cloth and Soil, wood, cloth and paper from arson should be packaged in small, clean metal cans

Firearms Make sure it is unloaded! Make sure it is unloaded! Do NOT place a pencil or other object in the barrel Do NOT place a pencil or other object in the barrel Record serial number, make, model and caliber of the gun. Record serial number, make, model and caliber of the gun. Mark it in some way. Place in cardboard Place in cardboardbox.

Bullets and Casings Do not use tweezers or pencil to pick up bullets and casings Do not use tweezers or pencil to pick up bullets and casings Wrap bullets in paper and place in separate envelopes Wrap bullets in paper and place in separate envelopes

Trace evidence vs. Control samples Control samples – samples from a known origin; used for comparison purposes Control samples – samples from a known origin; used for comparison purposes Examples: Examples: –For blood samples at a crime scene, collect control samples from victim and possible suspects –For paint, collect control samples from victim’s vehicle, suspect’s vehicle, bikes, etc. –For fibers, collect control samples from victim and suspect’s clothing, carpet, vehicle