AC1.3
Physical evidence
Physical evidence is that which is found at a crime and is a material thing. These can be
things found on a victim or suspect or can be items that a suspect is keeping in their
possession.
Hairs are a type of physical evidence which comes under the category of bodily fluids and
tissues, along with blood, saliva, semen, and skin flakes. Humans shed around 1 hundred
hairs from their heads everyday meaning that these can often be found at crime scenes.
Hairs can be analysed for DNA from cells in the hair’s root.
The processing of evidence involves 4 stages: collection, transfer, storage, and analysis.
These processes must be followed correctly in order for evidence to be admissible (seen as
valid in court).
Collection: Clear tape can be used by crime scene investigators to collect hairs that are not
immediately visible whilst tweezers can be used to collect visible hairs. Because hairs are
small great care must be taken in order to avoid losing them. Collected samples are put into
an envelope which is sealed and clearly marked with the contents. This is then sent to a
forensic lab for analysis. This evidence must be air dried before being packaged. Hairs can
also be collected from a victim or suspects head for comparison, using a comb. During
collection, crime scene investigators must wear protective suits with hoods as well as gloves
and masks to avoid contaminating the scene with their own hair or DNA.
Transfer: Hair fibres are transferred from the crime scene to the laboratory for analysis in a
truck. If drug analysis of hairs is going to be done, then samples have to get the lab within 3
months to be accurately tested.
Storage: Hair fibres must be kept dry and at room temperature when being stored. Hair can
be stored for over 20 years and still be used for DNA. Investigators or forensic experts are
responsible for ensuring evidence is correctly stored.
Analysis: Hairs can be analysed by forensic scientists in labs to see if they belong to a human
or animal. Where on the body a hair came from, and the race of its owner can also be
identified. Sometimes the way a hair became detached from the body (e.g., removed
forcibly or naturally) can be identified. Microscopical hair analysis can be done to look at
microscopic similarities and differences. DNA can also be extracted from cells on the roots of
hair. This can be compared to DNA databases to try and find a match. A toxicology report
can also be done on hair to determine whether the owner has been taking drugs in the past
3 months.
Hair evidence has been used in many real cases including the cases of Leanne Tiernan and
Barry George. Leanne Tiernan was abducted, sexually assaulted, and murdered by John
Taylor. He was linked to the crime as types of pollen found in Leanne’s hair, as well as her
skin and nasal cavities, matched that present in Taylor’s garden. This shows physical
evidence being used to gain a conviction. Barry George was falsely accused of the murder of
Jill Dando, an English journalist killed by a bullet shot at her head when she was at her front
Physical evidence
Physical evidence is that which is found at a crime and is a material thing. These can be
things found on a victim or suspect or can be items that a suspect is keeping in their
possession.
Hairs are a type of physical evidence which comes under the category of bodily fluids and
tissues, along with blood, saliva, semen, and skin flakes. Humans shed around 1 hundred
hairs from their heads everyday meaning that these can often be found at crime scenes.
Hairs can be analysed for DNA from cells in the hair’s root.
The processing of evidence involves 4 stages: collection, transfer, storage, and analysis.
These processes must be followed correctly in order for evidence to be admissible (seen as
valid in court).
Collection: Clear tape can be used by crime scene investigators to collect hairs that are not
immediately visible whilst tweezers can be used to collect visible hairs. Because hairs are
small great care must be taken in order to avoid losing them. Collected samples are put into
an envelope which is sealed and clearly marked with the contents. This is then sent to a
forensic lab for analysis. This evidence must be air dried before being packaged. Hairs can
also be collected from a victim or suspects head for comparison, using a comb. During
collection, crime scene investigators must wear protective suits with hoods as well as gloves
and masks to avoid contaminating the scene with their own hair or DNA.
Transfer: Hair fibres are transferred from the crime scene to the laboratory for analysis in a
truck. If drug analysis of hairs is going to be done, then samples have to get the lab within 3
months to be accurately tested.
Storage: Hair fibres must be kept dry and at room temperature when being stored. Hair can
be stored for over 20 years and still be used for DNA. Investigators or forensic experts are
responsible for ensuring evidence is correctly stored.
Analysis: Hairs can be analysed by forensic scientists in labs to see if they belong to a human
or animal. Where on the body a hair came from, and the race of its owner can also be
identified. Sometimes the way a hair became detached from the body (e.g., removed
forcibly or naturally) can be identified. Microscopical hair analysis can be done to look at
microscopic similarities and differences. DNA can also be extracted from cells on the roots of
hair. This can be compared to DNA databases to try and find a match. A toxicology report
can also be done on hair to determine whether the owner has been taking drugs in the past
3 months.
Hair evidence has been used in many real cases including the cases of Leanne Tiernan and
Barry George. Leanne Tiernan was abducted, sexually assaulted, and murdered by John
Taylor. He was linked to the crime as types of pollen found in Leanne’s hair, as well as her
skin and nasal cavities, matched that present in Taylor’s garden. This shows physical
evidence being used to gain a conviction. Barry George was falsely accused of the murder of
Jill Dando, an English journalist killed by a bullet shot at her head when she was at her front
