Effects of Ninhydrin Based Physical Processing of Latent Prints for Crime Investigations

Abstract

Detection of fingerprints at a crime scene is of prime interest to forensic investigators for identification purposes. Fingerprints are usually left at the scene of crime unintentionally after which they are detected and lifted using various methods. Ninhydrin is commonly used to reveal fingerprints on porous surfaces. It reacts with the amino group of amino acids and other components of palmar sweat to develop a purple color that is visible on most paper backgrounds. This technique was used to determine the effectiveness of Ninhydrin in developing latent prints. Once developed, latent prints should be photographed, because they fade with time. To prevent this they can be stored in airtight plastic bag after drying and only if they have reached optimum development. This empirical study confirmed the effectiveness of the Ninhydrin method for extracting fingerprints from documents like forged cheques, anonymous letters, and extortion notes. Further, this detection method can also be used to formulate a cost effective, easily understood procedure that can be adopted as a training tool for forensic, security training and law enforcement personnel.