WJEC Level 3 Diploma in Criminology
Unit 3, AC: 1.3
Model Write-up
Mark: 6/6
What you need to do:
- 6 marks = 30 minutes
- 2 subheadings:
1) Physical evidence
● Bodily fluids + trace evidence
● Fingerprints
● Impression evidence
2) Testimonial evidence
● These paragraphs don’t need to be in equal detail but must be
present to get above 3 marks
- All parts of process must be covered for both types of evidence
● Collection, transfer, storage, analysis, personnel
● Transfer and storage of testimonial evidence: write this - “Witnesses
may be interviewed by police, who will note it in their notebook where
they will formally write it up and store it on computer system
● Locard’s exchange principle not needed; mention all physical evidence;
cases needed; all processes (collection, transfer, personnel etc)
1) Physical evidence
Bodily fluids and trace evidence
Bodily fluids such as blood, semen, saliva, as well as tissues like skin flakes and hairs, can
provide crucial identification evidence. DNA can be extracted from these bodily fluids and
compared with control samples from suspects to determine if there is a match, potentially
placing the suspect at the crime scene. When collecting blood as evidence, it should be
allowed to air-dry. Wet blood-soaked fabric should not be folded, as it may cause the blood
to transfer to other parts of the item. Items with dry blood should be carefully packaged and
sent to the forensics laboratory for analysis as soon as possible, but definitely within 24
hours. Blood is typically stored in evidence bags in a refrigerator before being sent to the
police station for inclusion in the database. The personnel responsible for handling this fluid
are scientists in the forensics lab and the Crime Scene Investigation (CSI) team. Semen is
typically found in clothing or 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 put inside a
polythene bag. Each item should be packaged separately and appropriately labelled to
maintain the chain of custody and prevent cross-contamination. It is imperative that
individuals who have experienced sexual assault undergo a prompt examination by a police
surgeon or another medical professional, followed by the collection of swabs. At the scene of
a crime, it is possible to discover hair that could potentially be linked to a suspect. In
, instances of assault, the perpetrator may have the victim's hair on their person. If hairs are
discovered on garments, it is important to carefully wrap the item in paper or store it in a
paper bag, seal it, label it, and send it to the forensics laboratory for DNA analysis. Similarly,
individual hairs found on furniture should be wrapped or bagged in the same manner, as
DNA can be extracted from the root cells to identify either suspects or victims. Natural or
synthetic fibres can be found on clothing, carpets, and seats. To collect them, gloves and
tweezers are used, and then they are carefully wrapped in paper and sealed in a bag. These
samples are labelled and sent to a forensics lab for analysis, where experts determine the
type of fibre, its location at the crime scene, and attempt to match it to an individual. Clothing
fibres can vary in fabric mixes and dyes, often unique to specific manufacturers. This
valuable information can assist in identifying the source garment and contribute to the
compilation of a suspect description. Fibres, whether natural or synthetic, can be present on
clothing, carpets, and seats. To gather them, gloves and tweezers are employed, followed by
wrapping them in paper and sealing them in a bag. These samples are then labelled and
dispatched to a forensics lab for analysis. The lab examines the fibre type, its placement
within the crime scene, and endeavours to find a match to an individual. Clothing fibres
exhibit a wide range of fabric mixes and dyes, often exclusive to particular manufacturers.
This knowledge can be instrumental in determining the origin of the garment and can be
utilised to create a comprehensive suspect profile. Both natural and synthetic fibres can be
encountered on clothing, carpets, and seats. To collect these fibres, gloves and tweezers are
utilised, and they are subsequently carefully wrapped in paper and sealed within a bag.
These samples are then labelled and sent to a forensics lab for analysis. At the lab, experts
examine the fibre type, its location within the crime scene, and strive to identify a potential
match to an individual. Clothing fibres come in a diverse range of fabric mixes and dyes,
often specific to particular manufacturers. This valuable information aids in determining the
source garment and can contribute to the development of a suspect description. Stephen
Lawrence's case benefited greatly from the analysis of bodily fluids. A minute blood stain,
measuring 0.5mm x 0.25mm, was discovered on the collar of a bomber jacket. The jury was
informed that the chances of the DNA not belonging to Lawrence were less than one in a
billion. This finding strongly implicates Gary Dobson at the crime scene, as such a small
amount of blood would have dried rapidly. Additionally, trace evidence played a crucial role in
Lawrence's case. Fibres matching Lawrence's jacket and polo shirt were found on Dobson's
jacket, thanks to a taping technique used during the initial investigation. This further supports
the connection between Dobson and the crime scene.
Fingerprints
Fingerprints, being unique to each individual, serve as valuable identification evidence.
These distinct patterns are formed by skin ridges on the fingers and can leave impressions
or marks on various surfaces. These marks can be caused by sweat or contaminants on the
skin. Fingerprints can be classified into three types: latent prints, patent prints, and plastic
prints. Latent prints are invisible marks left on a surface, which can be made visible by
dusting with magnesium powder or using ultraviolet light. Once photographed, these prints
can be lifted using an adhesive strip and placed on an acetate sheet for further analysis.
Patent prints, on the other hand, are visible to the naked eye and can be left in substances
such as blood, ink, oil, powder, or dust. It is crucial to photograph these prints for analysis
and, if possible, preserve them for court proceedings. Lastly, plastic prints are
three-dimensional impressions created by pressing fingers into soft materials like wet clay or
putty. These prints should also be photographed for analysis, and if feasible, a mould should