Presumptive drug identification by ninhydrin fingerprint analysis

A known method of smuggling drugs into prisons is by infusing papers with these illicit substances, and sending them to prisoners through the mail. During the preparation of these drug-infused samples, there is potential for direct contact between the hands and paper, leading to the deposition of fingerprints. These fingerprints would not be visible to the naked eye, but can easily be rendered visible using the ninhydrin method for latent fingerprint detection. This reaction is well known to produce a visible purple coloured fingerprint on the surface of the material in a well-documented, consistent manner. This research, however, demonstrates variations of this reaction in the presence of illicit drugs on the surface of the paper being analyzed. The fingerprints have been demonstrated to vary in shade and intensity of colour in the purple/blue/grey region following the ninhydrin process when different drugs have been infused in the paper material. This phenomenon has the potential to be used as a presumptive indicator of any drugs that may be present in infused papers.