This is a document including full extensive notes and a full mark model answer onto Criminology Unit 3 (Crime scene to courtroom) 1.3. This can be used as inspiration for your brief for the controlled assessment, or taken into the controlled assessment for guidance. WARNING: you may be disqualified...
Note - 1.3 - Explai ho evidenc i processe
Ty[es of evidence:
Evidence is central to the process of investigating and prosecuting crime
because it is the basis on which a suspect is charged, tried and found either
guilty or not guilty. Therefore, the process of collecting and storing evidence must
be done with utmost care.There are many types of evidence, such as material
from the crime scene (e.g. fingerprints, blood stains), exhibits such as clothing,
CCTV footage, confessions and witness statements. However, we can group
evidence into two types:
Physical evidence: actual physical material, such as DNA extracted from blood
stains, weapons, stolen goods recovered from the suspect.
Testimonial evidence: written or oral statements by victims, eye witnesses, expert
witnesses and defendants.
Physical evidence
Physical evidence (also known as ‘real evidence’) is an important part of many
criminal investigations and collecting, transferring, storing and analysing it must
be done with great care to avoid contamination and to ensure it is admissible in
court.
Locard’s exchange principle
Edmond Locard (1877-1966) was a pioneer of forensic science and investigators
always worked on the basis of his exchange principle, which we summed up as
‘every contact leaves a trace’. In other words, material from the crime scene
(including from the victim) will be present on the o ender – and vice versa. Paul
Kirk describes the importance of the exchange principle and
physical evidence as follows:
“Where ever the o ender steps, whatever he touches, whatever he
leaves, even unconsciously, will serve as a silent witness against him.
Not only his fingerprints or his footprints, but his hair, the fibres from
his clothes, the glass he breaks, the tool mark he leaves, the paint he
scratches, the blood or semen he deposits or collects. It is factual
evidence. Physical evidence cannot be wrong, it cannot be wholly
absent. Only human failure to find it, study and understand it can
diminish its value.”
Di erent types of physical evidence need to be collected, transferred (e.g. to a
forensics laboratory) and stored in order to preserve them and to prevent
contamination.Most contamination occurs by handling items without gloves or by
breathing, sneezing or coughing over them .
, In the case of serious crimes (e.g. rape, murder or arson),investigators wear
protective clothing when collecting materials, to avoid contamination and
sometimes to protect themselves from hazardous substances. This includes a
mask, a hooded ‘scene suit’, overshoes and two
pairs of gloves.For less serious crimes, only a mask and gloves are required.
Bodily fluids and tissues
Bodily fluids such as blood, semen and saliva,and tissue such as skin flakes
and hairs, can provide important identification evidence, because DNA can be
extracted from them and compared with control samples from suspects to see if
there is a match which would put the suspect at the crime scene.BLOOD should
be allowed to air-dry. Fabric bearing wet blood should not be folded, as this will
cause the blood to transfer to other parts of the item.Items with dry blood on
them should be carefully packaged and sent as soon as possible and in any event
within 24 hours to the forensics laboratory for analysis.
SEMEN may be found on clothing and bedding.If wet, it should be allowed
to air-dry on the item. Once dry, the item should be placed in a paper bag, which
should then be sealed and . placed inside a polythene bag, again sealed and
labelled Each item should be packaged separately.Where someone has been the
victim of sexual assault, they should be examined as soon as possible by a police
surgeon or other doctor and swabs taken.
SALIVA from bites inflicted on a victim can also be swabbed to provide a
sample for DNA analysis. SKIN FLAKES We are constantly shedding small
quantities of skin. These may be found at the crime scene and can be analysed
for DNA.
HAIRS may be found at the crime scene that can be matched with those of
a suspect.In assault cases, a victim’s hairs may be found on the suspect.If hairs
are found on clothing the item should be wrapped in paper or placed in a paper
bag, sealed,labelled and sent to the forensics laboratory for analysis.Individual
hairs found on furniture etc. should be wrapped or bagged in the same way. DNA
can be extracted from cells in the root to identify suspects
or victims.
Fingerprints
Fingerprints (and palm, toe and sole prints) are unique to each individual
and so they are valuable identification evidence.The ‘prints’ are skin ridges on the
fingers and they can leave
impressions or marks in or on surfaces. The marks can be from sweat or from
contaminants on the skin. Once collected from the crime scene, fingerprints can
be compared with those stored in the police’s IDENT1 database, which houses
prints of all arrested persons, to see if there is a
match. Police also have Livescan scanners and Lantern portable units linked to
the database that can scan suspects’ prints and obtain a result within minutes.
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