A.C 1.3: Explain how evidence is processed
Evidence can be separated into two categories - physical and testimonial. It is paramount
that crime scene evidence is handled and processed with care, otherwise failure can lead to
severe consequences. For instance, a declaration that evidence is inadmissible at a trial, or a
conviction being overturned on appeal. This shows the magnitude of how important the
management of evidence is.
Physical Evidence
Physical evidence, commonly referred to as ‘real or ‘trace’ evidence is comprised of tangible
articles. This refers to fingerprints, fibres, and other biological matter, which will be
collected from a crime scene or a victims’ body. Locard’s Exchange Principal expresses that
every contact leaves a trace, meaning every time a person enters an environment, evidence
can be added or removed. Trace evidence refers to gunshot residue, clothing fibres and soil,
as they can be established between contact in individuals, or a person and an environment.
It was shown in the case of Barry George, who was convicted for the murder of Jill Dando
based on the evidence that there was gunshot residue in the pocket of his coat, which was
derived from police firearms and had been floating around his flat, meaning he was
innocent. A Scenes of Crime Officer will always adhere to the principal that physical
evidence will always be left at every crime scene.
An example of physical evidence is fibre and threads. These are often located on other items
or caught within another material; examined by a forensic scientist, who can decipher what
type of apparel or fabric it is. This evidence will be collected by gloved fingers (or with
tweezers) and wrapped in paper, then placed into a marked and sealed envelope.
Bodily fluids such as blood, semen and hair samples are other types of physical evidence. In
liquid form, blood can be collected on a sterile material and allowed to dry at room
temperature. It should be then transferred to a laboratory within 28 hours, so that a
forensic science can examine. However, if blood has been found dry, it should then be
placed in a sealed container and labelled. Semen stains usually correspond with a sexual
offence, meaning it is also important for the victim to be inspected by a doctor. This type of
evidence will be found on either clothing or bedding and should be left to dry. This is so the
material can be then wrapped in paper and placed in separate paper bags, as there may be
more than one item of clothing which presents semen on it. Finally, a hair sample is most
likely to be found in any environment where the victim was, however, will be on clothing.
This means that the clothing should be encased in paper and dispatched to the laboratory. A
positive of processing hair samples is that on examination, the race of the individual it
belonged to can be discovered.
Regarding fingerprints, there are two distinct types. Latent and patent. Latent fingerprints
are invisible, however with the surface being brushed with magnesium powder or exposure
by an UV light, they can become visible. After which they can then be photographed and
lifted by an adhesive strip and sent to the laboratory. If the fingerprints have been
impressed into a material, it will be placed on an acetate sheet and a photograph taken.
Plastic prints are also created by pressing a finger on a soft surface, such as window sealant
which will leave a 3D impression that can be lifted by a mould. However, patent fingerprints
are visible to the naked eye and will be left in liquid such as blood or oil. These can just be
photographed.
Impression evidence is a type of physical evidence where the suspect presses something
against a surface – in this instance a shoe print. If a shoeprint was to be left behind at a
crime scene, then police can check on the National Footwear Reference Collection, which
details different models and types of footwear. Multiple murders by Richard Ramirez were
Evidence can be separated into two categories - physical and testimonial. It is paramount
that crime scene evidence is handled and processed with care, otherwise failure can lead to
severe consequences. For instance, a declaration that evidence is inadmissible at a trial, or a
conviction being overturned on appeal. This shows the magnitude of how important the
management of evidence is.
Physical Evidence
Physical evidence, commonly referred to as ‘real or ‘trace’ evidence is comprised of tangible
articles. This refers to fingerprints, fibres, and other biological matter, which will be
collected from a crime scene or a victims’ body. Locard’s Exchange Principal expresses that
every contact leaves a trace, meaning every time a person enters an environment, evidence
can be added or removed. Trace evidence refers to gunshot residue, clothing fibres and soil,
as they can be established between contact in individuals, or a person and an environment.
It was shown in the case of Barry George, who was convicted for the murder of Jill Dando
based on the evidence that there was gunshot residue in the pocket of his coat, which was
derived from police firearms and had been floating around his flat, meaning he was
innocent. A Scenes of Crime Officer will always adhere to the principal that physical
evidence will always be left at every crime scene.
An example of physical evidence is fibre and threads. These are often located on other items
or caught within another material; examined by a forensic scientist, who can decipher what
type of apparel or fabric it is. This evidence will be collected by gloved fingers (or with
tweezers) and wrapped in paper, then placed into a marked and sealed envelope.
Bodily fluids such as blood, semen and hair samples are other types of physical evidence. In
liquid form, blood can be collected on a sterile material and allowed to dry at room
temperature. It should be then transferred to a laboratory within 28 hours, so that a
forensic science can examine. However, if blood has been found dry, it should then be
placed in a sealed container and labelled. Semen stains usually correspond with a sexual
offence, meaning it is also important for the victim to be inspected by a doctor. This type of
evidence will be found on either clothing or bedding and should be left to dry. This is so the
material can be then wrapped in paper and placed in separate paper bags, as there may be
more than one item of clothing which presents semen on it. Finally, a hair sample is most
likely to be found in any environment where the victim was, however, will be on clothing.
This means that the clothing should be encased in paper and dispatched to the laboratory. A
positive of processing hair samples is that on examination, the race of the individual it
belonged to can be discovered.
Regarding fingerprints, there are two distinct types. Latent and patent. Latent fingerprints
are invisible, however with the surface being brushed with magnesium powder or exposure
by an UV light, they can become visible. After which they can then be photographed and
lifted by an adhesive strip and sent to the laboratory. If the fingerprints have been
impressed into a material, it will be placed on an acetate sheet and a photograph taken.
Plastic prints are also created by pressing a finger on a soft surface, such as window sealant
which will leave a 3D impression that can be lifted by a mould. However, patent fingerprints
are visible to the naked eye and will be left in liquid such as blood or oil. These can just be
photographed.
Impression evidence is a type of physical evidence where the suspect presses something
against a surface – in this instance a shoe print. If a shoeprint was to be left behind at a
crime scene, then police can check on the National Footwear Reference Collection, which
details different models and types of footwear. Multiple murders by Richard Ramirez were
