L5: Forensic Strategies, evidence recovery song evidential value Flashcards
what was the Rolex murder?
Husband and wife attacked outside their house.
steal two rolexes.
wife shot and died.
husband hit their car
what evidence was there?
fragments of getaway car found on husbands car( glass and paint)
bag of clothes from ones ex girlfriend
who was arrested for the Rolex case?
Jason James and Daniel Whyte - life imprisment
what evidence did the duffle coat provide?
gun shot residue and DNA profile of Jason James
in a burglary what evidence could there be?
finger marks around entrance tool mark son door fibres on door shoe marks hai or fibres
how do you priorities evidence?
evidential value
nature of crime
cost-effectiveness
what evidence is prioritised?
finger marks - cheap high value
blood - DNA
shoe marks - cheap fairly useful
whats a volume crime?
opportunity theft, criminal damage
whats a major crime?
unexplained death, rape, missing child
what is evidence retrieval and subsequent examination determined by?
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
what are the critical areas to collect evidence from?
Those likely to yield most evidence
Those that will allow further examination to progress
what is a control?
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.
what is a reference?
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.
How are finger prints recovered?
- non pourras surface is dusted with powder and lifted
- paper taken to lab
- photograph if in blood
How are shoe marks recovered?
- 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
How are tool marks recovered?
- 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
what are the 3 types ofDNA samples?
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
what are sources of DNA evidence ?
blood traces, semen, vaginal fluid, sweat and urine, saliva
are blood traces a good source of DNA?
excellent, stain drys naturally
are semen traces a good source of DNA?
excellent, aspermia or sperm depleted semen possible profile from cells shed during ejaculation
Is vaginal fluid a good source of DNA?
ok due to lining cells, may be in present semen
are sweat and urine a good source of the DNA?
not useful unless cells present
are saliva a good source of DNA?
DNA from buccal cells from mouth
cells not from the liquid saliva
Is hair a good source of DNA?
- 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
is faeces a good source of DNA?
Only mitochondrial DNA obtainable
is Dandruff, surface skin cells a good source of DNA?
Only low copy number (LCN) DNA
analysis possible
are fingernail clippings a source of DNA?
Preferable to scrapings
OK for STR profiling only if blood present
How to preserve DNA?
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
How to recover fibres?
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
How to recover fibres?
tape lift mount on acetate sheet envelope tape envelope label where lift happened
How to recover hair?
control hair pulled by root
head 25
pubes 10
How to recover glass?
collect 6 pieces from broken area
not floor unless necessary
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