Searching and Collection Flashcards
Search Methods
Line/Strip: lanes, often outdoors
Line: many searchers in a line
Circle: spiral in or out, explosive scenes
Zone: already defined zones, house, car
Evidence Types
- Physical (objects)
- Observations (weather)
- Testimony (witness)
Evidence Collection
- Selectivity based on lab capabilities
- Best Evidence Rule - whole item
- Questioned and known samples
- wet/bloodstained items should be air dried and packaged in paper or in a cooler
- volatile liquids should be airtight
- Use tamper evident seals
PPE Levels
A: IDLH, self contained breathing apparatus
B: High respiratory protection, moderate skin
C: Air-purifying respirator, moderate skin
D: risk of splash or inhale, basic PPE
Process of collecting trace evidence
- Use forceps, tweezers, by hand, tape lift, vacuum
- Collect large evidence, collect trace evidence, dust for prints
Primary and Secondary Transfer
Primary: first movement of something
Secondary: second movement of something
Firearm collection
Safety: unload weapons, photograph first
- place in container with barrel noted outside
- if found in water, transport with some
Bullet and cartridge collection
- rubber coated or heavily taped tools
- structure may be removed for embedded bullets
- place in a pill box or vial
Fiber evidence collection
- smallest unit of a textile, length>width
- try to ID and preserve ‘carriers’
- relevant clothing in paper bags
- fibers in druggist folds
Daughter Exhibit
secondary evidence associated with another
Bio-fluids and Pathogens
- A huge safety concern
- include blood, saliva, semen, urine, feces, vaginal secretions
- plague (160-270 days in remains)
- tetanus (48 days in blood)
- HIV (15 days in liquid, 6 days in bones)
- Hep A/B/C (100x more likely than HIV)
- Tuberculosis (200 years in remains)
HVS - DNA
3 types: cigarette butts, envelope cutouts, swabs with suspected DNA
- presumptive tests done after collection
- Max 3 items per case
VCS - DNA
- Entire item when possible
- no previous testing done
Comparison Samples (VCS and HVS)
Blood finger-pricks, oral/buccal swabs, discards (cigarettes, gum) and personal items (razors, toothbrushes)
How much DNA is there?
- 1 drop saliva: 150ng
- 1 drop blood: 900ng
- 1 drop semen: 1500ng
- 1 pulled hair w/ root: 10-500ng
