Chemical techniques used for fingerprints detection.pptx

Chemicals used for fingerprint detection

1. NAME- SOHAM BHATTACHARYA BRANCH- B.SC FORENSIC SCIENCE SUBJECT- FORENSIC DERMATOGLYPHICS

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- A n 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  fingerprints ). Fingerprint are not permanent and the developed fingerprints should be immediately photographed. For fixation of fingerprints , starch is used that give the fingerprint a blue-black color and fix it for weeks to months.

8. For field use(in mobile crime team) iodine fuming kits were given to experts. In iodine fuming kit glass tube ,  I odine 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).