L5: Forensic Strategies, evidence recovery song evidential value Flashcards Preview

1st Year sem 1: Forensic Science Principles > L5: Forensic Strategies, evidence recovery song evidential value > Flashcards

Flashcards in L5: Forensic Strategies, evidence recovery song evidential value Deck (32)
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1
Q

what was the Rolex murder?

A

Husband and wife attacked outside their house.
steal two rolexes.
wife shot and died.
husband hit their car

2
Q

what evidence was there?

A

fragments of getaway car found on husbands car( glass and paint)
bag of clothes from ones ex girlfriend

3
Q

who was arrested for the Rolex case?

A

Jason James and Daniel Whyte - life imprisment

4
Q

what evidence did the duffle coat provide?

A

gun shot residue and DNA profile of Jason James

5
Q

in a burglary what evidence could there be?

A
finger marks around entrance 
tool mark son door 
fibres on door 
shoe marks 
hai or fibres
6
Q

how do you priorities evidence?

A

evidential value
nature of crime
cost-effectiveness

7
Q

what evidence is prioritised?

A

finger marks - cheap high value
blood - DNA
shoe marks - cheap fairly useful

8
Q

whats a volume crime?

A

opportunity theft, criminal damage

9
Q

whats a major crime?

A

unexplained death, rape, missing child

10
Q

what is evidence retrieval and subsequent examination determined by?

A

Cost-effectiveness for various evidence types
o Forensic work in-house by police is cheaper than bought-in analyses
o Need to provide early leads to the investigation (investigative forensics) o Need to identify (and exclude) individuals
o Need to provide strong evidence in support of a prosecution in court

11
Q

what are the critical areas to collect evidence from?

A

Those likely to yield most evidence

Those that will allow further examination to progress

12
Q

what is a control?

A

control is a standard material that may be needed in an analysis to ensure that it does not interfere with the analysis of the evidential material itself.

13
Q

what is a reference?

A

reference is a sample of material that is similar or may be identical to the evidential material where it is intended that this sample be subjected to a comparative analysis with the evidence itself.

14
Q

How are finger prints recovered?

A
  • non pourras surface is dusted with powder and lifted
  • paper taken to lab
  • photograph if in blood
15
Q

How are shoe marks recovered?

A
  • Photographed, enhanced, lifted at the scene
  • Marks in dust – electrostatically lifted
  • Marks in soft ground – lifted using a casting material to give a 3D profile
16
Q

How are tool marks recovered?

A
  • Where the action of a tool deforms the surface
  • Photographed at the scene
  • Remove item/ surface to laboratory or
  • Used a plastic casting compound to get a 3D profile of the mark
17
Q

what are the 3 types ofDNA samples?

A

o Where the action of a tool deforms the surface
o Photographed at the scene
o Remove item/ surface to laboratory or
o Used a plastic casting compound to get a 3D profile of the mark

18
Q

what are sources of DNA evidence ?

A

blood traces, semen, vaginal fluid, sweat and urine, saliva

19
Q

are blood traces a good source of DNA?

A

excellent, stain drys naturally

20
Q

are semen traces a good source of DNA?

A

excellent, aspermia or sperm depleted semen possible profile from cells shed during ejaculation

21
Q

Is vaginal fluid a good source of DNA?

A

ok due to lining cells, may be in present semen

22
Q

are sweat and urine a good source of the DNA?

A

not useful unless cells present

23
Q

are saliva a good source of DNA?

A

DNA from buccal cells from mouth

cells not from the liquid saliva

24
Q

Is hair a good source of DNA?

A
  • Pulled hairs are OK for STR profiling

- Shed hairs or hair shaft are not suitable for STR but may be use for mitochondrial DNA analysis

25
Q

is faeces a good source of DNA?

A

Only mitochondrial DNA obtainable

26
Q

is Dandruff, surface skin cells a good source of DNA?

A

Only low copy number (LCN) DNA

analysis possible

27
Q

are fingernail clippings a source of DNA?

A

Preferable to scrapings

OK for STR profiling only if blood present

28
Q

How to preserve DNA?

A
Scrape or cut dried material
Do not touch pulled hair roots
Avoid storage in warm, moist conditions o Freeze swabs as soon as possible
Air-dry wet materials
Polythene bags ONLY for dried material
29
Q

How to recover fibres?

A

o Tape-lift, mount on acetate sheet , packaged in poly bag or envelope and taped at all seams and openings.
o Ensure exact location of lift is documented on the label
o For control samples (e.g. Carpets, upholstery), submit more than just tape-lifts; tape-lift exhaustively

30
Q

How to recover fibres?

A
tape lift
mount on acetate sheet
envelope
tape envelope
label where lift happened
31
Q

How to recover hair?

A

control hair pulled by root
head 25
pubes 10

32
Q

How to recover glass?

A

collect 6 pieces from broken area
not floor unless necessary
package ad label