Unit 3 AC1.3 – Processing evidence
Physical evidence:
- Physical evidence is tangible evidence that can be collected at crime scenes to prove the
innocence or guilt of a person. Physical evidence can include hair, fibre, footprints,
fingerprints and ballistics. These can be left in the environment by the offender where the
crime took place.
Hair and fibre:
- To collect this evidence, crime scene investigators (CSI) is involved. They will wear special
suit so they don’t contaminate any evidence at the crime scene. Hair is picked up with
special tweezers while fibre is picked up using tape. Hair is then placed in a sealed tube to
reduce the likelihood of contamination, and the fibre is stuck to a piece of paper to be easily
picked up. This evidence is then transferred to hair and fibre analysis experts for further
examination to determine who it belongs to. Hair allows experts to find the race of a person,
where from the body it came from and if it has been dyed. They can also see if the hair was
pulled from the roots and if so, DNA can be collected from the scalp follicles.
- A real life case where hair and fibre solved a case was in the Stephen Lawrence case. Fibres
from Stephen’s polo and jacket, and blue-green acrylic from the cuff and wristband of
Stephen’s jacket was found on Gary Dobson’s clothing. David Norris was also linked to the
crime as experts found two hairs that contained Stephen’s DNA, one was 1mm and the other
2mm in length, in the evidence bag and has Norris’ jeans.
- In the scenario, a red scarf was brought up by a member of the public that could have been
either the victims or Hughe’s and could provide any hair and fibre DNA.
Footprints:
- The CSI are responsible for collecting footprints. There are two ways to collect footprints: 3D
and flat prints. To collect 3D prints, a casting paste is poured onto the footprint and allowed
to set. Then it is dug up with the mud and transferred to a box to reduce contamination and
destruction. Flat prints are collected using an ESLA machine that attracts dust particles to the
shoe print to make it visible for a picture to be taken as a form of storing the flat print as
evidence. Footprint experts will look at these prints at the laboratory and compare any wear
and tear or distinctive details of the suspects shoes. To compare the flat prints, they will take
a transparent picture of the footprints and place it on top of the suspect shoe. The data can
be stored in footwear data base and look for matches. If there are no matches, a Cinderella
analysis, which looks at the insoles for any toe prints, will take place.
- A real life case where footprints were used is in the OJ Simpson case where an expert
testified that there was bloody footprints near Nicole Simpson’s home that were of size 12,
the same as OJ Simpson’s shoe size.
- In the scenario, officers were able to find many footprints in the initial investigation which
can be collected as evidence.
Fingerprints:
Physical evidence:
- Physical evidence is tangible evidence that can be collected at crime scenes to prove the
innocence or guilt of a person. Physical evidence can include hair, fibre, footprints,
fingerprints and ballistics. These can be left in the environment by the offender where the
crime took place.
Hair and fibre:
- To collect this evidence, crime scene investigators (CSI) is involved. They will wear special
suit so they don’t contaminate any evidence at the crime scene. Hair is picked up with
special tweezers while fibre is picked up using tape. Hair is then placed in a sealed tube to
reduce the likelihood of contamination, and the fibre is stuck to a piece of paper to be easily
picked up. This evidence is then transferred to hair and fibre analysis experts for further
examination to determine who it belongs to. Hair allows experts to find the race of a person,
where from the body it came from and if it has been dyed. They can also see if the hair was
pulled from the roots and if so, DNA can be collected from the scalp follicles.
- A real life case where hair and fibre solved a case was in the Stephen Lawrence case. Fibres
from Stephen’s polo and jacket, and blue-green acrylic from the cuff and wristband of
Stephen’s jacket was found on Gary Dobson’s clothing. David Norris was also linked to the
crime as experts found two hairs that contained Stephen’s DNA, one was 1mm and the other
2mm in length, in the evidence bag and has Norris’ jeans.
- In the scenario, a red scarf was brought up by a member of the public that could have been
either the victims or Hughe’s and could provide any hair and fibre DNA.
Footprints:
- The CSI are responsible for collecting footprints. There are two ways to collect footprints: 3D
and flat prints. To collect 3D prints, a casting paste is poured onto the footprint and allowed
to set. Then it is dug up with the mud and transferred to a box to reduce contamination and
destruction. Flat prints are collected using an ESLA machine that attracts dust particles to the
shoe print to make it visible for a picture to be taken as a form of storing the flat print as
evidence. Footprint experts will look at these prints at the laboratory and compare any wear
and tear or distinctive details of the suspects shoes. To compare the flat prints, they will take
a transparent picture of the footprints and place it on top of the suspect shoe. The data can
be stored in footwear data base and look for matches. If there are no matches, a Cinderella
analysis, which looks at the insoles for any toe prints, will take place.
- A real life case where footprints were used is in the OJ Simpson case where an expert
testified that there was bloody footprints near Nicole Simpson’s home that were of size 12,
the same as OJ Simpson’s shoe size.
- In the scenario, officers were able to find many footprints in the initial investigation which
can be collected as evidence.
Fingerprints:
