Evidence CollectionEvidence Collection

Notes on Page 60-61Notes on Page 60-61

What evidence?What evidence?

What types of evidence should be What types of evidence should be collected at a crime scene?collected at a crime scene?– Any physical evidence: blood, bodily Any physical evidence: blood, bodily

fluids, hair, fibers, glass, paint, fluids, hair, fibers, glass, paint, flammable liquids (in cases of arson), flammable liquids (in cases of arson), firearms, tool marks, fingerprintsfirearms, tool marks, fingerprints

Collecting bloodCollecting blood

Wet blood should be picked up using Wet blood should be picked up using sterile gauze padssterile gauze pads

Allow to air dry and then refrigerate Allow to air dry and then refrigerate or put in freezer (to prevent or put in freezer (to prevent

denaturing)denaturing) Do NOT dry in direct Do NOT dry in direct

sunlight; do NOT heat sunlight; do NOT heat

bloodblood

Collecting bloodCollecting blood

For dried blood, package material For dried blood, package material (sheet, shirt, clothing, etc.) in brown (sheet, shirt, clothing, etc.) in brown paper bagpaper bag

Place each separate stain in its own Place each separate stain in its own bagbag

Do not use moistened cloth or paper Do not use moistened cloth or paper to clean stainsto clean stains

Bodily fluidsBodily fluids

Semen, saliva, urineSemen, saliva, urine Allow to air dry, then package in Allow to air dry, then package in

separate brown paper bagsseparate brown paper bags Follow same standards as for bloodFollow same standards as for blood

Hair and fibersHair and fibers

Pick up with fingers or tweezersPick up with fingers or tweezers Place in paper bindle or coin Place in paper bindle or coin

envelopeenvelope Can be picked up using tape, but Can be picked up using tape, but

only if it is allowed by the laboratory only if it is allowed by the laboratory operating in your areaoperating in your area

Paint samplesPaint samples

More useful if you have several More useful if you have several layers in the paint samplelayers in the paint sample

Use a clean knife blade to carefully Use a clean knife blade to carefully scrape or flake the paint sample offscrape or flake the paint sample off

Place samples in Place samples in

paper bindles, then paper bindles, then

in small envelopesin small envelopes

Flammable Liquids (arson)Flammable Liquids (arson)

Check everywhere…mattresses, rugs, Check everywhere…mattresses, rugs, upholstery, walls, woodupholstery, walls, wood

If liquids are in open containers, pour If liquids are in open containers, pour some into a glass vial and secure to some into a glass vial and secure to make it airtightmake it airtight

Soil, wood, cloth and Soil, wood, cloth and

paper from arson should paper from arson should

be packaged in small, be packaged in small,

clean metal cansclean metal cans

FirearmsFirearms

Make sure it is unloaded!Make sure it is unloaded! Do NOT place a pencil or other object Do NOT place a pencil or other object

in the barrel in the barrel Record serial number, make, model Record serial number, make, model

and caliber of the gun. and caliber of the gun.

Mark it in some way.Mark it in some way. Place in cardboard Place in cardboard

box.box.

Bullets and CasingsBullets and Casings

Do not use tweezers or pencil to pick Do not use tweezers or pencil to pick up bullets and casingsup bullets and casings

Wrap bullets in paper and place in Wrap bullets in paper and place in separate envelopesseparate envelopes

Trace evidence vs. Control Trace evidence vs. Control samplessamples

Control samples – samples from a known Control samples – samples from a known origin; used for comparison purposesorigin; used for comparison purposes

Examples: Examples: – For blood samples at a crime scene, collect For blood samples at a crime scene, collect

control samples from victim and possible control samples from victim and possible suspectssuspects

– For paint, collect control samples from For paint, collect control samples from victim’s vehicle, suspect’s vehicle, bikes, victim’s vehicle, suspect’s vehicle, bikes, etc.etc.

– For fibers, collect control samples from For fibers, collect control samples from victim and suspect’s clothing, carpet, vehiclevictim and suspect’s clothing, carpet, vehicle

Scenario

The body of a scientist is discovered in the science lab. The body is located in the corner of the classroom in a sprawled position, face-up. The victim is wearing a disguise of some kind and a small amount of dirt is lying nearby. A broken beaker is found next to an overturned microscope. It appears the victim may have attempted to identify the aggressor by writing an incriminating note, which is found torn and crumpled next to the body. Blood, hair and fiber evidence are collected at the scene along with a variety of fingerprints.