These are summary notes on the whole of AC1.3, they include information on: Physical evidence (bodily fluids, blood stains, fingerprints, shoe impressions & trace evidence) and Testimonial evidence (eyewitnesses & expert witnesses). My notes also include relevant case studies and Locard's exchange ...
AC 1.3 – controlled assessment planning sheet – ‘QUALITY NOT QUANTITY’
Testimonial evidence – Written or verbal statements from a defendant, victim or witness. It must comply with the rules of evidence to be admissible in court. [The Colin Stagg case – all the
evidence gathered through the polices ‘honeytrap’ was dismissed by the judge, as it did not comply with the rules of evidence] In court testimonial evidence is given in the witness box,
where the opposite side can question their statements, however if the witness is considered ‘vulnerable’ they may join via a video link.
Physical Evidence – A.K.A. Real evidence, it includes palpable articles (fibres, hairs, weapons etc.). Scenes of crimes officer's work under the assumption that there is physical evidence left at
every crime scene (Locard’s exchange principle). But it can cause problems in [The Barry George case – wrongly convicted of murder as 1/10,000 of 1cm of gun residue was found on his
jacket].
Outdoor crime scene – Vulnerable to the loss or contamination of evidence, especially if the crime scene is not cordoned off properly, as the public could alter or wreck evidence. Weather
conditions are also a problem with outdoor crime scenes, as evidence can be destroyed in storms and rain. The media has more access to a crime scene if its outside, which could lead to
contamination. To avoid these problems police must secure the scene by putting up tent s to protect the area from the weather and block reporters from taking pictures.
Locard’s exchange principle – Suggests that whenever an individual enters any environment something (DNA) will always be added/removed from it, it can also explain contact between
individuals. It is described as ‘every contact leaves a trace’. Dr Edmund Locard was a forensic scientist from France who was a leading influence in forensic science.
Evidence How is this evidence processed? (Collection, Transfer, Link to case study/ example: (further reading and Key terms and equipment/
Storage and analysis) research can be used not just the cases mentioned in class) techniques used:
Collection Mark Twitchell Automated Haematology
- Must be a llowed to air dry at room temperature Murdered Johnny Altinger in 2008 by luring him to a rented Analysers – Count the number
- Dry blood is collected with a cotton swab and put in a labelled test garage, after pretending to be a female on a dating website. of cells in a piece of DNA,
tube Police ordered luminol tests after finding small blood splatters, measure them and analyse their
- Fabric with wet blood should NOT be folded (to prevent transfer) the tests revealed excessive amounts of human blood pooled in genetic make-up.
- If it's still liquid it should be collected with a gauze/cotton pad and the garage.
then placed on sterile material to dry thoroughly. Polymerase Chain Reaction –
- Careful not to contaminate stains with each other Uses a small sample of genetic
material to duplicate DNA and
Gloves should always be worn create millions of copies.
Transfer
Physical Items with dry blood should be packaged and sent to the forensic lab
– for analysis within 28 hours.
bodily fluids
Storage
Blood - If the blood is dried on the material, it will be placed in a container
then sealed properly and labelled.
stains
- All evidence is packaged separately to avoid contaminating the
stains with each other.
Analysis
, - Luminol is used to see if there is blood present, as the chemical
reacts with the haemoglobin in our blood creating a blue light when
in darkness.
- Analysed to see if the blood is from the victim or offender, through
testing the blood type.
- Scientists can also check if the individual had a blood infection,
was taking medication, drugs or alcohol. It's also possible to see
how long the blood has been at the scene.
Scientists will use:
Automated Haematology Analysers – Count the number of cells
in a piece of DNA, measure them and analyse their genetic make-
up.
Polymerase Chain Reaction – Uses a small sample of genetic
material to duplicate DNA and create millions of copies.
Collection Carroll Bonnet Livescan scanners and Lantern
Latent prints Stabbed to death in his apartment in 1978. Police found portable units analyse and scan
- Become visible with ultra-violent light, powder or chemicals. fingerprints in his bathroom, as the killer had tried to wash the a suspects fingerprints (Works
- Lifted by brushing over the fingerprints with a magnesium powder blood of his hands, however they couldn’t match the fingerprint. quick, getting a result in
mixed with superglue, then using an adhesive strip and placing it on In 2008 the case was re-opened, and the prints were tested again minutes).
an acetate sheet. with new technology called the ‘Integrated Automated
- Prints can also be impressed by pressing the print with your hand Fingerprint Identification System’ (IAFIS) which matched the
into a soft material. fingerprint to Jerry Watson in less than 5 hours. Watson was
Physical - If the prints are fragile a mould can be made. sentenced to life in prison.
– Patent prints
Fingerprints - Not touched as they are visible to the naked eye. Richard Ramirez ‘The Night Stalker’
In 1984 and 1985 Ramirez murdered 13 people through home
Latent All prints should be photographed invasions and assaults. A teenager reported a suspicious car
(Invisible) driving through a housing estate, the car was later found
Transfer abandoned. The car had fingerprints inside, which were tested
- Sealed and sent to the lab and identified as Richard Ramirez, who was sentenced to death.
Patent Storage
(Visible) - In evidence boxes (Latent)
- On computers (Patent)
- All fingerprints are stored in the ‘IDENT1’ database.
Analysis
- Forensic scientists examine the prints for patterns or distinctive
marks.
- Compared to ‘IDENT1’ database using a microscope (See if they
match)
Forensic scientists use:
Livescan scanners and Lantern portable units analyse and scan a
suspect's fingerprints (Works quick, getting a result in minutes).
- Results double checked by human analysis.
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