Aim :Sample is collected to conduct
the forensic examination in order to
prove or disprove whether there is a
link between individual(s) & the
objects and the place of evidence .
Forensic specimen collection
When collecting specimens for
forensic analysis, the following
principles should be strictly adhered
Avoid contamination: Ensure that
specimens are not contaminated by
other materials. Wear gloves at all times.
Modern DNA assay systems are very
sensitive and may detect small amounts
of extraneous material.
Collect early: Try to collect forensic
specimens as soon as possible.The
likelihood of collecting evidentiary
material decreases with the passing of
time. Ideally, specimens should be
collected within 24 hours of the assault;
after 72 hours, yields are reduced
Handle appropriately: Ensure that
specimens are packed, stored and
As a general rule, fluids should be
refrigerated; anything else should be
Label accurately: All specimens must
be clearly labeled with the patient’s
name and date of birth, the type of
specimen, and the date and time of
Ensure security: Specimens should
be packed to ensure that they are
secure and tamper proof. Only
authorized people should be entrusted
Maintain continuity: Once a specimen
has been collected, its subsequent
handling should be recorded.
Details of the transfer of the specimen
between individuals should also be
It is advisable to check with local
authorities regarding the protocols for
the recording of such information.
Document collection: It is good
practice to compile an itemized list in
the patient’s medical notes or reports
of all specimens collected and details
of when, and to whom, they were
Common requirements are:
swabs,sterilewater, syringes,scalpel or
blade ,foreceps ,plastic
wares,brownpaper, EDTA tubes,zip
slides,preservates,tubes, lifting tape,
clipper Pen/board marker
cotton guage etc.
Methods of collection:
Whole blood sample: sterile needle
should be used while collecting blood
and put in EDTA vial.if blood is pooling
then collect on sterile cotton or gauze
Blood stain: should be picked up on
sterile cotton guage using sterile
foreceps and blade.
If blood stain is,
On clothing,if possible,wrap the item in
clean paper,place the article in a brown
paper bag or box and seal & label
On small solid objects,send the whole
stained object to the lab,after labelling
On large solid objects:It is usually
impractical to deliver the whole object
to the Laboratory, scrape the stain
onto a clean piece of paper, which can
be folded and placed in an envelope.
Seal and mark the envelope.
. Do not mix dried stains. Place each
stain in a separate envelope.
. Never attempt to wipe dried stains
from an object using a moistened cloth
. Dried blood stain can also be
collected by using lifting tape :
For dried blood stains on a non-
absorbent surface, fingerprint lifting
tape may be placed over the stain and
The stain is transferred to the
adhesive side of the tape, which may
then be secured on a clear piece of
acetate for submission to the
Seminal stain: Should not be touched
by hand especially the stain portion.
Should be picked up with sterile
Hard Tissues( Bones): Bones should
be picked up using gloves, Kept at a
place where there are no chances of
environmental contamination. It should
be allowed to dry completely.
Soft Tissues: Body organs should be
collected using forces and wearing
gloves. these should be kept in a
Hair: Hair roots are preferred for the
analysis. Hair roots should be picked
up using sterile forceps.
Buccul sample: should be collected by
using dry sterile swab in whole mouth
between cheeks and gums,on and
under tongue, in dentile fissures.
Skin: drip 3-4 drops of sterile water on
swab & roll it on body with moderate
pressure and immediately roll another
dry swab on same area.
Fingernails: analysis for recovery of body
fluids/DNA/other materials or comparison
with broken fingernails at the scene.
Clip the fingernail of one hand at the
time, over paper or drape & pack
separately in addition to this swab under
nails ,on surface of nail and around
Table :DNA content of biological
TYPE OF SAMPLE AMOUNT OF DNA
liquid blood 20000-40000 ng/ml
bloodstain 250-500 ng/cm2
liquid semen 150000-300000 ng/ml
hair with root 1-10 ng/root
liquid saliva 1000-10000 ng/ml
oral swab 100-1500 ng/swab
bone 3-10 ng/mg
tissue 50-500 ng/mg
Precautions for sample
Wear gloves. Change them often.
Use disposable instruments or clean them
thoroughly before and after handling each
Avoid touching the area where you believe
DNA may exist.
Avoid talking, sneezing, and coughing over
Avoid touching your face, nose, and mouth
when collecting and packaging evidence.
Air-dry evidence thoroughly before
Put evidence into new paper bags or
envelopes, not into plastic bags. Do not use
Package all biological evidence in
paper bags or envelopes (do not use
The packaging of biological evidence
in plastic or airtight containers must
always be avoided, because the
accumulation of residual moisture
could contribute to the growth of DNA-
destroying bacteria and fungi.
Whole Blood: Blood should be collected
in sterile container containing an
anticoagulant. The mostly preferred is
It should be mixed properly but gently for
some time. The container should be
covered with parafilm to avoid slippage.
Should be kept it at 40C or using ice
during transportation till it reaches
laboratory for analysis
Blood stain: Blood stain should be
dried properly. In semi dry stain there,
is a possibility of bacterial growth thus
chances of having contamination.
After complete drying it should be
wrapped in a fresh blotting paper and
packed in a Zip lock poly bag.
No preservative is required. It can be
transported at environmental
Seminal stain: Likewise seminal stain
should also be dried properly. In semi dry
stain there, is a possibility of bacterial
growth thus chances of having
After drying it should be wrapped in a
fresh blotting paper and packed in a
Zip lock poly bag.
No preservative is required. It can be
transported at environmental
Hard Tissue: No preservative is required.
The hard tissues should be wrapped in
the blotting paper and placed in a zip
lock poly bag.
Soft tissue: It should be placed at 40C or
in Ice till it reaches laboratory for
Hair: Hair roots should be placed in a
blotting paper and then packed in a zip
lock poly bag. It requires no preservative
and can be transported at environmental
Buccul sample: should be collected on
sterile swab and swab should be placed
in tube. storage can be done by freezing.
Skin: sample collected by swab should
be placed in tube and then in tamper-
evident bag. Storage by freezing.
Fingernails:collected by clipping on
paper should be packed in zip lock poly
bag/tamper evident bag along with
clipper , swabs used should be placed in
tube and store by freezing.