In the past century, forensic investigators have universally accepted fingerprinting as a reliable identification method, which relies mainly on pictorial comparisons. Despite developments to software systems in order to increase the probability and speed of identification, there has been limited success in the efforts that have been made to move away from the discipline's absolute dependence on the existence of a prerecorded matching fingerprint. Here, we have revealed that an information-rich latent fingerprint has not been used to its full potential. In our approach, the content present in the sweat left behind-namely the amino acids-can be used to determine physical such as gender of the originator. As a result, we were able to focus on the biochemical content in the fingerprint using a biocatalytic assay, coupled with a specially designed extraction protocol, for determining gender rather than focusing solely on the physical image.

In the past century, forensic investigators have universally accepted fingerprinting as a reliable identification method via pictorial comparison. One of the most traditional detection methods uses ninhydrin, a chemical that reacts with amino acids in the fingerprint content to produce the blue-purple color known as Ruhemann's purple. It has recently been demonstrated that the amino acid content in fingerprints can be used to differentiate between male and female fingerprints. Here, we present a modified approach to the traditional ninhydrin method. This new approach for using ninhydrin is combined with an optimized extraction protocol and the concept of determining gender from fingerprints. In doing so, we are able to focus on the biochemical material rather than exclusively the physical image.

The Bradford reagent, comprised of the Coomassie Brilliant Blue G-250 dye, methanol, and phosphoric acid, has been traditionally used for quantifying proteins. Use of this reagent in the Bradford assay relies on the binding of the Coomassie Blue G-250 dye to proteins. However, the ability of the dye to react with a small group of amino acids (arginine, histidine, lysine, phenylalanine, tyrosine, and tryptophan) makes it a viable chemical assay for fingerprint analysis in order to identify the biological sex of the fingerprint originator. It is recognized that the identification of biological sex has been readily accomplished using two other methods; however, both of those systems are reliant upon a large group of amino acids, 23 to be precise. The Bradford assay, described here, was developed specifically to aid in the transition from targeting large groups of amino acids, as demonstrated in the previous studies, to targeting only a single amino acid without compromising the intensity of the response and/or the ability to differentiate between two attributes. In this work, we aim to differentiate between female fingerprints and male fingerprints.