DNA item examination

Question 1

What is the max size of the sample

Answer 1

1.5ml in microcentrifuge tube

Question 2

what is the best source of DNA

Answer 2

body fluids (blood semen or saliva)

Question 3

Swabs

Answer 3

• Swabs of items are often submitted to lab

- Simply cut off swab heads and submit

Question 4

Cigarette ends

Answer 4

• Cut put approx. 5mm^2 from paper at smoke end avoid filter

Question 5

Chewing gum

Answer 5

• Cut out approx. 5mm^3 from gum and submit, easier to handle if frozen

Question 6

Hairs

Answer 6

• Need root material for standard DNA profiling
• Re0mve 5mm from end
• If more than one hair and confident of same type combine up to five roots

Question 7

Drink containers

Answer 7

• Swab around mouthpiece to recover possible saliva

- Avoid visible staining from drink

Question 8

touch DNA

Answer 8

• Can be sampled from almost any item
• Need to think about where to target
• How has it been used/worn
• Need a logical approach that you could defend in court

Question 9

sample methods

Answer 9

• Double swabbing methods- wet and the dry swabs, used distilled water
• Use tweezers with small pieces of filter paper to get into small spaces
• Taping for larger, absorbent surfaces

Question 10

considerations

Answer 10

• Sample should be given a unique identifier
• Contemporaneous notes
• Maintain chain of custody
• Anti- contamination measures
• Clean bench between items
• Separate treatment of crime scene and reference items

Question 11

notes and photos

Answer 11

• Contemporaneous notes
• Sample may well change after sampling
• This is your chance to record the item ‘as received’