forensics evidence collection

collecting evidence

each type has specific ways of collection, must be place and labeled differently

biological samples

could get bacterial/fungal contamination, place in airtight container

for all evidence

photograph first, proper collection, fill out bag and add to evidence log, fresh gloves for each item, seal and sign

dry, solid trace examples

hairs, fibers, soil/glass particles, broken nails

dry, solid trace

tweezers, vacuum, scraping, combing, clipping, tape lifting --> bindle, package separately into envelope/bag and seal, collect fingernail scrapings with dull pick like toothpick

dry, solid large

pick up, cut out, grab carefully, package separately and seal, if sharp, blade wrapped in cardboard before going in bag

dry, solid large examples

soda can, small carpet, document/letter

wet samples (biological)

extreme care, swab and then allow to dry to prevent mold/bacteria + degradation, if it can't dry package in plastic to prevent cross contamination, the bindle, paper enevelope and label biohazard

wet samples (biological) examples

wet blood, wet saliva, wet semen

extra wet sample info

entire item can be collected and swabbed, like a bloody shirt or carpet (cut), if a sample is found dry, swab with dampened distilled water, contaminated samples can be purfied

dry samples (biological)

handle with extreme care, take entire item if possible, paper envelope label biohazard, of sample is nonporous (water doesn't go through), you can scrap the sample

firearms

bullets and casing are trace evidence, outside cannot be touched bc fingerprints, be safe and pick up by handle, never point, keep unloaded, note down condition and steps to make it safe without destroying it, package separate from ammo/magazine

impression evidence

make a cast of impression if it isn't permanent (soil or snow), type depends on material, collect if permanent

impression evidence examples

shoes, tires, toolmarks, bitemarks

arson evidence

ash and soot collected in new, clean paint cans, collect from different areas but pay attention to origin and use separate cans for each area

why we use cans for arson

because it is volatile (evaporates easily) and cans are airtight, only pack 1/2-2/3 of can, room for gas

standard/reference samples

physical evidence with the origin known, can be compared to crime scene

standard/reference examples

blood/hair/soil from suspect, soil samples compared with crime soil, blood from victim compared to suspect, all medications, hair, fingerprints

control samples

charred carpet (accelerant residue) compared to undamaged carpet, if suspicious cheical is in charred, evidence on deceased, autopsies if these chemicals are found, get all evidence before buried or lost, take pics, clothes, fingernail scrapings, blood, dna, once buried, need court to get out (exhumation)

computer crimes evidence

those who seize devices with evidence cannot handle it much, turn on, or extract data, handled by special group

computer crime examples

telephones, computers, ipods, mp3

chain of custody

item collected, people have to sign before receiving, note down where evidence is/has been, if broken, integrity lost, make sure info is accurate with paperwork, be very specific and don't assume when reporting facts, put back in evidence locker

testimonies to evidence

1. piece of evidence is what it purports to be

2. continuous possession by each individual

3. it remained in same condition

packaging

1. description of items that is generic

2. where it was found

3. name and number

4. date and time

5. name of staff

paperwork is not enough

process of packaging

picture first, then proper collection, fill out the bag/envelope, add to evidence catalog, use fresh gloves, place in bag, seal, sign and date