Trace Evidence Flashcards
What is trace evidence?
Physical evidence found in small amounts at crime scenes e.g. fibres, glass, hairs, residues
How do recover glass from a broken window?
- take 6 individual pieces from the frame of each broken pane
- label what side of glass is inside/outside
- ..
How do you recover glass shards?
- Scoop/tweezer into universal tube (~15 pieces)
- Document in MO if scoop is used
- Seal edge of universal tube and put in tamper evident bag
Do you recover window glass from the floor?
NO only as a last resort, document where it has been recovered from
What types of clothing has the greatest retention of glass shards?
Coarse knitted items and tweed
What is the difference between float and tempered glass shards?
Float: large, ‘traditional’ shards
Tempered: tiny square shaped shards
What is backwards fragmentation?
Where lots of glass will fall in the direction of where the force originated from
What are the factors that affect fibre transferral?
- Number of contacts
- Pressure of contacts
- Length of contacts
- Texture of recipient garment/surface
What types of clothing have the least amount of retention in terms of glass shards?
Cotton, denim
What factors affect the retention of glass shards on clothes?
- Texture
- Washing
- Activity
- Time worn
What other factors will affect how many fibres are recovered from a garment?
- If it was worn after the offence
- If washed
- Length of time worn
- Texture of the garment
How do you recover visible fibres?
- Tweeze into universal tube if possible and put in tamper evident bag
- Apply tape to surface, put on acetate, secure edges then place into tamper evident bag
- ALWAYS recover TWEEZERS
How do you recover latent fibres?
Apply tape to surface, place on acetate, secure edges, put in tamper evident bag
What areas do you fibre lift in a car?
Headrest, seat belt, seat base, seat back, interior of the door
What areas do you fibre lift in a car boot?
L side, R side, back fo seats, underneath of parcel shelf (if there is one), halve base and 1 for each side
When taking shards from double glazed units, do you package the shards from each pane as 1 exhibit or separately?
Package separately, as two separate exhibits
How is paint transferred within a crime scene?
Forceful contact OR contact with disturbed paint i.e. flaky, peeling
What does paint consist of?
Binder, additives, pigment
How do you recover paint samples?
- Photograph
- Scrape down to original surface in a 2x2cm square
- Seal in universal tube, tamper evident bag
- Secure scalpel in box/tube and package with the paint sample
- ALSO take a CONTROL sample
