The effect of fingerprint enhancement methods applied on adhesive surfaces on DNA recovery: a preliminary study

Abstract

The presence of body fluids such as blood, saliva, semen or urine during fingerprint research on the evidence taken from the crime scene makes it necessary to protect biological materials to examine the evidence in multiple ways. Therefore, it is crucial that fingerprint development (FD) techniques do not disrupt the structure of biological materials during FD procedures. In this sense, it is essential to determine whether biological material or fingerprints should be the priority during the collection of evidentiary materials, to determine the systematic order and to determine whether the FD methods to be applied cause damage to the genetic material used in the identification of individuals and to evaluate them in terms of their evidentiary quality. This study investigated the effects of the application of trace detection methods on DNA profiling processes in evidence where fingerprints and biological samples are found at the same time. In this study, blood, saliva, semen and urine samples were taken from a male individual who signed an informed consent form at the laboratory stage. The samples were applied 50 µL on the adhesive tape surface. After application, the samples were treated with crystal violet (CV) and sticky side (SS) fingerprint development chemicals suitable for the surface type. The prepared samples were dried under room conditions. After 1 day and 45 days under normal room conditions, silica-based DNA extraction was performed. After extraction, DNA quantification was performed using the fluorimetry method. In the study, biological samples with known DNA content were used to focus on DNA quantification. Among the fresh samples prepared in the study, DNA recovery was higher in the SS-treated urine, blood and saliva samples and in the CV-treated semen sample group compared to the other groups. This shows that chemical treatment of some biological samples on adhesive tape increases the efficiency of DNA recovery. When the 45-day waiting samples were compared with the control group samples, DNA recovery decreased in CV-treated urine and blood samples, while DNA recovery increased in SS-treated urine and blood samples. In semen samples, both CV and SS treatment negatively affected DNA recovery. In saliva samples, DNA recovery increased ~2-fold in the CV-treated sample group, while SS treatment caused a ~75% decrease in DNA recovery. The results show that the non-porous adhesive tape does not adversely affect the amount of DNA in terms of STR profiling of latent FD chemicals used on the surfaces and that adhesive tape treated with fingerprint enhancement chemicals can actually be used for advanced forensic genetic analyses for DNA extraction on surfaces.