Unit 23A: Forensics Evidence, Collection and Analysis
Gathering and preserving Forensic Evidence
Procedure Description Justification
Cordons A cordon is a security measure Using cordons helps prevent
to maintain safety. The cordons loss or destruction of physical
will act as a barrier and access evidence. For example,
to the area is controlled, making footprints, fibres and
sure that all evidence is bloodstains.
undisturbed. A cordon can be
set up with high visibility tape,
barriers and even a person.
Observing and One of the first stages upon Photography shows factors,
recording of the scene arrival at a crime scene is to such as location, condition
Photography observe and record the and relationship of evidence
environment before any (surroundings). These can
evidence is touched. later be represented in court.
Photography is used to record Recording the appearance of
evidence, such as footwear the whole crime scene before
impressions, tool marks, blood stepping in is important. This
pattern and injuries. The three prevents contamination and
different types of photography ensures that an accurate
are mid-range, overview and record is created of what the
close-up photographs. scene looked like, so CSI’s
Photographs must show points (Crime Scene Investigator)
of entry and exit, in order to are able to reconstruct the
maintain integrity of evidence. scene.
Videography Videography is commonly used Videography provides an
in the investigation of serious overall view of the crime
crimes. For example, murder, scene. Video footage
fraud and serious assault. enhances understanding of
Videography is used to record a the crime scene. This can be
large amount of information, used as evidence in court.
which can be used by police and Videography is extremelly
forensic scientists to examine. useful as it helps establish
Cameras which have special real-time perspective of the
features, like powerful zoom crime scene, which can help
options and full high definition later with identification.
are used.
Sketching Rough sketches are made, Sketches provide an overall
measurements are recorded, perspective and accurate
and scale is determined. dimensions. However, they
are complex to understand.
Identifying and This systematic approach starts Investigators focus on
targeting evidence off with securing the scene to identifying evidence. For
avoid contamination. example, biological evidence,
Investigators perform a like blood, hair and bodily
procedure called a walk-through fluids. Blood degrades
to get an overview of the whole quickly, which means it
, crime scene, taking notes, such needs urgent handling, if not
as, location of the scene, date handled immediately there
and time it was committed. may be loss of evidence.
Characterisation and Characterisation of evidence is Characterisation identifies
comparison of using all evidence found to the type of evidence and
evidence reconstruct the crime scene, by where it may have come
examining the physical and from. Procedures like DNA
chemical properties of the Analysis can be used to
evidence. For example, if a identify individuals based on
weapon is used, the forensic their unique genetic code.
scientist is able to link the Comparison of evidence is
fingerprints to the suspect. useful for investigators
Comparison of evidence is because it helps link them to
examining two or more items to a suspect. In this case,
check if they share a common contact traces could be
origin. For example, observing considered from footwear
footprints for patterns that marks.
match with the suspect.
Prevention of Contamination is the unwanted The prevention of
contamination transfer of material, such as contamination is important
fingerprints and fibers. It is because it maintains the
highly important to avoid integrity of evidence.
contamination, especially at the An example of evidence
crime scene. This ensures that which can be contaminated is
the wrong person does not get unsealed packaging. This can
accused. Equipment including be prevented by using the
oversuits, disposable gloves, correct type of packaging
hairnets and masks are used to and sealing carefully,
prevent transferring their own ensuring there is no loss of
DNA. Special protocols are evidence.
followed for packaging evidence.
Methods of Impression evidence, for Footwear marks could
collecting evidence example, footwear is collected provide details about the
Casting by using casting Mould. This is footwear, such as, make, size
stored in a cardboard box, to and wear pattern of the shoe.
prevent cracks. If no suspect is Imprints can also be
found, other strategies like enhanced to show more
crime scene intelligence are subtle features, such as wear
used. marks.
Figure 1
Figure 1 above shows footwear marks which have been recovered from the crime scene. The
investigator is wearing Personal Protective Equipment (PPE). This helps prevent
contamination.
Swabbing Swabbing is a technique Swabbing is crucial for
Gathering and preserving Forensic Evidence
Procedure Description Justification
Cordons A cordon is a security measure Using cordons helps prevent
to maintain safety. The cordons loss or destruction of physical
will act as a barrier and access evidence. For example,
to the area is controlled, making footprints, fibres and
sure that all evidence is bloodstains.
undisturbed. A cordon can be
set up with high visibility tape,
barriers and even a person.
Observing and One of the first stages upon Photography shows factors,
recording of the scene arrival at a crime scene is to such as location, condition
Photography observe and record the and relationship of evidence
environment before any (surroundings). These can
evidence is touched. later be represented in court.
Photography is used to record Recording the appearance of
evidence, such as footwear the whole crime scene before
impressions, tool marks, blood stepping in is important. This
pattern and injuries. The three prevents contamination and
different types of photography ensures that an accurate
are mid-range, overview and record is created of what the
close-up photographs. scene looked like, so CSI’s
Photographs must show points (Crime Scene Investigator)
of entry and exit, in order to are able to reconstruct the
maintain integrity of evidence. scene.
Videography Videography is commonly used Videography provides an
in the investigation of serious overall view of the crime
crimes. For example, murder, scene. Video footage
fraud and serious assault. enhances understanding of
Videography is used to record a the crime scene. This can be
large amount of information, used as evidence in court.
which can be used by police and Videography is extremelly
forensic scientists to examine. useful as it helps establish
Cameras which have special real-time perspective of the
features, like powerful zoom crime scene, which can help
options and full high definition later with identification.
are used.
Sketching Rough sketches are made, Sketches provide an overall
measurements are recorded, perspective and accurate
and scale is determined. dimensions. However, they
are complex to understand.
Identifying and This systematic approach starts Investigators focus on
targeting evidence off with securing the scene to identifying evidence. For
avoid contamination. example, biological evidence,
Investigators perform a like blood, hair and bodily
procedure called a walk-through fluids. Blood degrades
to get an overview of the whole quickly, which means it
, crime scene, taking notes, such needs urgent handling, if not
as, location of the scene, date handled immediately there
and time it was committed. may be loss of evidence.
Characterisation and Characterisation of evidence is Characterisation identifies
comparison of using all evidence found to the type of evidence and
evidence reconstruct the crime scene, by where it may have come
examining the physical and from. Procedures like DNA
chemical properties of the Analysis can be used to
evidence. For example, if a identify individuals based on
weapon is used, the forensic their unique genetic code.
scientist is able to link the Comparison of evidence is
fingerprints to the suspect. useful for investigators
Comparison of evidence is because it helps link them to
examining two or more items to a suspect. In this case,
check if they share a common contact traces could be
origin. For example, observing considered from footwear
footprints for patterns that marks.
match with the suspect.
Prevention of Contamination is the unwanted The prevention of
contamination transfer of material, such as contamination is important
fingerprints and fibers. It is because it maintains the
highly important to avoid integrity of evidence.
contamination, especially at the An example of evidence
crime scene. This ensures that which can be contaminated is
the wrong person does not get unsealed packaging. This can
accused. Equipment including be prevented by using the
oversuits, disposable gloves, correct type of packaging
hairnets and masks are used to and sealing carefully,
prevent transferring their own ensuring there is no loss of
DNA. Special protocols are evidence.
followed for packaging evidence.
Methods of Impression evidence, for Footwear marks could
collecting evidence example, footwear is collected provide details about the
Casting by using casting Mould. This is footwear, such as, make, size
stored in a cardboard box, to and wear pattern of the shoe.
prevent cracks. If no suspect is Imprints can also be
found, other strategies like enhanced to show more
crime scene intelligence are subtle features, such as wear
used. marks.
Figure 1
Figure 1 above shows footwear marks which have been recovered from the crime scene. The
investigator is wearing Personal Protective Equipment (PPE). This helps prevent
contamination.
Swabbing Swabbing is a technique Swabbing is crucial for
