2. CONTENT
• Introduction.
• Types Of Fingerprints.
• What is Chemical Techniques used for Fingerprint Detection?
• Different Chemicals Used for Detection of Fingerprints.
• Chemical Techniques used for detection of Fingerprints.
3. INTRODUCTION
My Topic- Detection Of Fingerprints by Chemical Techniques
Definition of Fingerprints- An impression or mark made on a surface by a
person's fingertip, which is used for identifying individuals from the
unique pattern of whorls and lines on the fingertips.
Forensic Use- Fingerprints are commonly used to understand the
individuality of a person so as to reveal his or her identity. Hence, there
are chances of occurrence of fingerprints in all crimes and these
impressions works as an evidence for identification of person involved
in any crime.
4. TYPES OF FINGERPRINTS
• Latent Fingerprints are made of the sweat and oil on the skin’s surface.This type of
fingerprint is invisible to the naked eye and requires additional processing in order
to be seen.
• Patent fingerprints, on the other hand, can be made by blood, grease, ink, or dirt.
This type of fingerprint is easily visible to the human eye.
• Plastic fingerprints are three-dimensional impressions and can be made by
pressing your fingers in fresh paint, wax, soap, or tar. Just like patent fingerprints,
plastic fingerprints are easily seen by the human eye and do not require additional
processing for visibility purposes.
5. CHEMICAL TECHNIQUES USED FOR DETECTION OF FINGERPRINTS
The Process in which different types of chemicals are use to develop and
detect different types of fingerprints which are collected from crime
scene and may be a vital evidence and help the court to give conviction
or justice in different types of cases.
6. DIFFERENT CHEMICALS USED FOR DETECTION OF FINGERPRINTS
• Iodine Fumes
• Ninhydrin
• Silver Nitrate
• Amido Black
7. CHEMICAL TECHNIQUES USED FOR DETECTION OF
FINGERPRINTS.
Iodine Fuming- Iodine fuming is a very old but effective method.
It is very convenient to use. Non-destructive(stains are temporary), fast and cheap.
The process of iodine fuming is done by two methods, in both the principal is same but
processing is
different. First one is a lab process -
In a lab process iodine fuming is done inside a chamber. First step is to set up the fuming
chamber
and place the iodine crystals . Iodine crystals are sublime at room temperature ( directly
change from
solid to gas ) and you can also place hot water into the chamber.You can use a paper clip and
a stiff
wire to suspend the specimen into the chamber. Wait for 5 to 10 minutes the iodine crystals
filled the
chamber with violet vapors. Check the specimen.The brown (yellowish brown) color
fingerprints
were developed on the specimen. ( Iodine fumes are absorbed by the fat and oil deposits of
the latent
8. For field use(in mobile crime team) iodine fuming kits were given to experts.
In iodine fuming kit glass tube , Iodine crystals , blowing tube , filtering wool ,
calcium carbonate granules (drierite is
used in some kits) is present .
First we place wool then calcium carbonate then again wool then Iodine crystals and
again wool one by one.(some forensic companies provide partially pre-assembled set
with rubber stoppers on both sides).
Next step is to blow (by vinyl tube or in some by rubber pump) the tube from one
side to warm the iodine crystals. Iodine crystals release the vapors which fumed to
the targeted print from other end of tube. Make a distance of one inch between the
tube end and the target area. Grab the tube tightly so some heat of hand also
transferred to the tube.(some modern versions use battery power for heat and some
has disposable iodine fuming guns).
