Simultaneous labeling of multiple components in a single fingermark

A fingermark contains important forensic information of the donor, not only in its ridge pattern, but also in the chemical composition of its secretion. Detection and identification of these secretions can be done by immunolabeling. In this study, we describe for the first time a reproducible immunolabeling method that allows the simultaneous detection of multiple components of interest. This method not only reduces the manipulation of fingermarks, but also different types of information can be obtained about the donor in one labeling session. To prove the concept of this technique, we selected two general components as antigens of interest, dermcidin and the human serum albumin. Conjugation of both antibodies to two different synthetic fluorophores, followed by simultaneous incubation of both conjugated antibodies, resulted in successful multiple immunolabeling of fingermarks left on a porous nitrocellulose membrane and on a non-porous glass slide surface. In order to minimize false positives to prevent non-specific binding of antibodies to fingermarks and surface carriers, careful blocking and washing steps were found crucial. With this reproducible protocol, high quality images could be obtained from the multiple labeled fingermarks. In conclusion, simultaneous multiple immunolabeling of antibodies in fingermarks can identify specific components in the secretion of the fingermark, including components related to hygiene, diet, time of day, contacts gender and drug use. Multiple immunolabeling therefore has the potential to make a major impact in the forensic field.