Fingerprinting Techniques

In simple words, a fingerprint is the impression created by friction ridges present on fingers. Fingerprint of every person in the world is unique and is studied in forensic science. The fingerprints, lifted using any one of the fingerprinting technique, can thus, be analyzed and used in the process of identification of a person. The fingerprinting history can be traced back to the times of Babylonian and Chinese civilization.

Different Fingerprinting Techniques
These techniques have undergone a lot of change from the time they originated. The use of digital scanning equipment helps in comparing number of samples and thereby helping in proper identification. Before understanding the techniques of fingerprint identification being used, let us have a look at the types of fingerprints. There are basically 3 types of fingerprints i.e. visible, plastic and latent. The visible fingerprint is the one which is made with ink (generally wet substances) and can be seen easily. The plastic fingerprint is one that is made with materials like wax, soap, etc. The last type is known as latent fingerprint. The impressions created on a surface by means of perspiration or natural oils are termed as latent fingerprints. It is very difficult to identify latent fingerprints.

Traditional Technique
The traditional or most common technique of fingerprinting is taking impressions of a person's hand with the help of ink. Pressing fingers covered in ink, on to a paper is the way of obtaining fingerprints.

Digital Scanning Technique
A sensitive touch-pad is used to capture the fingerprints of a person or a suspect in this method. The impression of fingerprint recorded on the touch-pad is then compared with thousands of impressions with the help of software or stored in the system, if there is no matching fingerprint in the database of the computer.

Lifting Technique
In this technique, oil from hands which are left behind are captured by means of powders made from resinous polymers. To make the identification process convenient, dark-colored powders are used on light surfaces and vice versa. In order to enhance (lift) the fingerprints on porous materials, chemicals such as Ninhydrins are used. The super glue chamber is used to place object taken from the site of crime. The glue present in these chambers adhere to the fingerprints and thereby makes them visible.

Laser Technique
The laser technique is one of the most useful for capturing fingerprints. In this fingerprinting technology, the fingerprints from many different surfaces can be lifted by means of laser.

Bullet Fingerprinting
The bullet fingerprinting technique is special in a sense that it is possible to visualize the fingerprint even after its removal from the surface in question. This technique works on the concept of analyzing the interactions which took place between the sweat of fingerprint and metal. The use of advanced surface imaging techniques is made in bullet fingerprinting. These surface imaging techniques make use of the atomic force microscope. This microscope can make nano-scale observations of brass samples that are fingerprinted. The observations help in identifying conditions which can help in the promotion of natural enhancement of fingerprints. This technique is considered as a sure shot method of fingerprint identification, because even wiping and washing of the surface cannot remove the sweat gland deposits completely.

There are many concepts related to fingerprinting that need to be understood. The field of fingerprint identification is highly specialized. The different fingerprinting techniques explained above give a rough idea about how the investigation is carried out.