The Relationship between Dna Content and Autofluorescence of Fingermarks: a Preliminary Study

Obtaining full DNA profiles from latent fingermarks is a difficult task. DNA levels in fingermarks are typically below or close to detection limits and highly variable between fingermarks. Currently, methods which can estimate in situ the DNA content non-destructively are lacking. In order to determine whether the intensity of autofluorescence light can be used to indicate the DNA content in fingermarks, in this pilot study, the relationship between DNA content and autofluorescence of fresh fingermarks is investigated. Thereto, fingermarks were left half on white tiles and half on plastic sheets. The partial marks on white tiles were used to evaluate the intensity of autofluorescence of the fingermarks using a UV crime-lite® torch. The part of the fingermark left on plastic sheets was used for human-specific DNA quantification. Autofluorescence images were digitally recorded and their intensities were off-line determined subjectively by multiple observers. For statistical analysis a Spearman’s rank correlation analysis was performed. In two of the three series a moderate, but significant correlation could be found between the DNA content and the autofluorescence of the fingermarks. However, this correlation is too weak to guide the forensic investigator reliably to the fingermarks with a substantial DNA content.