Unit 23; forensic evidence, collection and analysis
Assignment B (BPU)
Content page
B1; collection of biological evidence
. blood, hair, fibers (human and animal), saliva, semen, fingerprints, bones
B2; collection of chemical evidence
. Drugs - Class A, B or C
. firearm discharge residue
. poisons - anions, corrosive poisons, gaseous and volatile poisons, metal and metalloid
poisons, pesticides, and toxins
B3; collection of physical evidence
. footprint - 2 dimensional and 3 dimensional
. bullets and cartridges
. firearms; handguns, rifles, shotguns
. documents - handwritten and printed documents
. IT; mobile phones, computer, tablets, and CCTV
B4
. prevention of contamination
. records
. security
. full documentation of procedures and methods
Crime scene report
Crime scene number 578
Laboratory robbery
Lab trashed + lab equipment stolen
Scene - lab assistant unconscious on floor
Biological evidence - blood, hair and fibers, fingerprints,
Chemical evidence - poisons, white powder
Physical evidence - hammer, footprints, broken glass
, B. P3
Time of evidence collected Evidence tag Description of evidence images
number
9.00am 1 Biological evidence
Photograph taken of
detected fingerprint on
conical flask Lifting taping
method used in which tape
is applied to the fingerprint
and lifted up copying the
fingerprint on the tape
which is then put on a
latent card to preserve the
evidence.
9.05am 2 Chemical evidence
Unknown blue powder
found on the floor of the
crime scene. Drug test kits
can be done on the spot of
the scene to identify the
name of the blue powder.
Spatula is used to collect
the powder and placed in
a sealed plastic bag to be
transported to toxicology
laboratory for examination
,9.10am 3 Physical evidence
Broken glassware located
on the floor of the crime
scene. Broken Glass is
placed in a sealed paper
bindle and then put in
labeled plastic bag
9.12am 4 Chemical evidence
Unknown white powder
identified on the floor near
the victim's body. Drug
test kits can be applied on
the spot to identify the
substance and its
structure Spatula is used
to scoop up the white
substance and then
placed in a sample tubes
to be sent for further
testing
9.15am 5 Biological evidence
Blood located near the
victims head in which
blood possibly coming out
of the victim head. Wet
cotton swabs are rubbed
on the blood after it has
been dampened with
distilled water. Once
collected the cotton swabs
are placed in a transport
tubes and sent to the
forensic lab
,9.20am 6 Biological evidence
Strands of hair located on
the body of the
victim.Tweezers are used
to pick up the hair and
then placed in a labeled
plastic bag to be delivered
to laboratory for deeper
testing of the evidence
9.22am 7 Biological evidence
Fibers detected on the
floor near the victim.
Tweezers or filtered
vacuum cleaners are used
to collect the fibers and
placed in a labeled plastic
bag.
,9.25am 8 Physical evidence
Photograph taken of
Hammer left at the crime
scene on the floor. Width
and length of hammer is
measured and then
packaged in a large plastic
evidence bag to be
delivered to the laboratory
9.29am 9 Physical evidence
Footprints of the possible
suspect identified on the
floor. gelatin lifter in which
footprints found on
surfaces such as
cardboard, fabric, or wood
floor is lifted up by rubber
sheets in which on one
side contains a low
adhesive gelatin layer
, B.P4
Collection of biological evidence
Collection of Blood
Sterile swabs are commonly used to collect blood that is in its liquid state; the liquid
blood is then collected and placed in transport sample tubes to be sent to the lab. Dried
Blood can also be present at the scene in which the blood stain can be dampened
using distilled water to therefore allow the blood to be swabbed. Clothing containing
blood that is dried can be packaged and labeled in plastic labeled bags.[1]
Collection of Saliva and semen
Wet cotton swabs are commonly used to collect samples by rubbing the saliva
and semen present on the victim, suspect or on items and surfaces . Once then
the cotton swab is then packaged and sealed and in small bags to be sent to the
laboratory. Saliva analysis can be used for DNA profiling to reveal [2]
Collection of bones
Bones are photographed and packaged when being handpicked using gloves
which are then placed in large plastic bags and labeled correctly. Handpicking is
most commonly for collection of bones to prevent contamination and damage
resulting in inaccurate interpretation and examination of the bone. Once
transported to the lab a forensic anthropologist will analyze the bone sample.
Bone analysis can reveal how the deceased persons died, when they died and
sex of the deceased person bone by examining different parts of bones such as
skull or pelvis [1]
Fingerprints
Fingerprints left at the crime scene are normally dusted with black powder. Once
fingerprints are detected it is then photographed using lifting tape the fingerprint
is then removed from the object or surface it was identified from and put down a
latent lift card to allow the evidence to be preserved. Fingerprints can reveal the
identity of the suspect's fingerprints [3]
Hair and fibers
Hair and fibers from human and animal present at the scene such as on the floor
or on the clothing of the victim if there's been physical contact is collected using
tweezers, filtered vacuum, and tape. It is then packaged in a small plastic bag
and sent to the lab for further examination. Hair analysis can be used to
determine the race, sex and color of the hair from the individual narrowing down
suspects to only specific suspects that match the criteria of the hair sample[4]
