This study investigates methods for obtaining high-quality touch DNA from a nonporous surface after latent fingerprint collection.
This study concludes that viable touch DNA often remains after tape-lifting a fingerprint; thus, it is highly recommended for crime scene investigators to swab the surface area of latent fingerprints after lifting if DNA typing is desired. These surface swabs, if used in conjunction with other samples taken from the same source, may be enough to improve an otherwise null or nonprobative STR profile to one that is sufficient for human identification. This valuable source of contributor touch DNA should not be overlooked. Fingerprints were initially collected for human identification via ridge pattern analysis; however, successful DNA typing has been generated from fingerprints as well. For nonporous surfaces, fingerprints are typically tape-lifted and transferred to paper backing cards for storage. In this study, to avoid swabbing fingerprints directly for DNA, and thus destroying the ridge pattern, the original surfaces were swabbed for residual touch DNA that may have been left behind after lifting. Despite obtaining null STR profiles, high-quality, quantifiable DNA from the majority of the samples was detected (90 fingerprints tested). A subset of the samples underwent post-amplification purification to attempt to improve STR allele detection; however, no STR allele peaks were detected. (Published Abstract Provided)