Comprehensive examination of conventional and innovative body fluid identification approaches and DNA profiling of laundered blood- and saliva-stained pieces of cloths

Abstract

Body fluids like blood and saliva are commonly encountered during investigations of high volume crimes like homicides. The identification of the cellular origin and the composition of the trace can link suspects or victims to a certain crime scene and provide a probative value for criminal investigations. To erase all traces from the crime scene, perpetrators often wash away their traces. Characteristically, items that show exposed stains like blood are commonly cleaned or laundered to free them from potential visible leftovers. Mostly, investigators do not delegate the DNA analysis of laundered items. However, some studies have already revealed that items can still be used for DNA analysis even after they have been laundered. Nonetheless, a systematical evaluation of laundered blood and saliva traces that provides a comparison of different established and newly developed methods for body fluid identification (BFI) is still missing. Herein, we present the results of a comprehensive study of laundered blood- and saliva-stained pieces of cloths that were applied to a broad range of methods for BFI including conventional approaches as well as molecular mRNA profiling. The study included the evaluation of cellular origin as well as DNA profiling of blood- and saliva-stained (synthetic fiber and cotton) pieces of cloths, which have been washed at various washing temperatures for one or multiple times. Our experiments demonstrate that, while STR profiling seems to be sufficiently sensitive for the individualization of laundered items, there is a lack of approaches for BFI with the same sensitivity and specificity allowing to characterize the cellular origin of challenging, particularly laundered, blood and saliva samples.

The stability and persistence of blood and semen mRNA and miRNA targets for body fluid identification in environmentally challenged and laundered samples

“…The transfer of blood specific mRNA has also been previously reported by van den Berge et al [35]. Samples washed without the addition of other clothes did not exhibit any transfer of mRNA, which is also consistent with several previous studies [19,34,35]. The blood miRNA target (miR-451a) was detected in all unstained cuttings, and transfer of the semen specific target (miR-891a) was observed in half of the unstained samples.…”

“…2). Previous studies [20,34] have also reported diminished visibility of bloodstains on materials washed at higher temperatures (60-95°C). The mRNA and miRNA results of the laundry study can be seen in Fig.…”

“…elevated wash temperature or washed twice) had a lower occurrence of mRNA transcript detection, though a more thorough investigation is needed for any definitive conclusions. Kulstein et al [34] also observed HBB in stains washed once at 40°C, but did not observe any body fluid specific markers in warmer washes or in items washed twice. This discrepancy may be due to differences in length of wash cycles (2 hours compared to 30 minutes in this study), leading to more thorough stain removal, or differences in analysis methods (capillary electrophoresis-based assay and RT-qPCR).…”

DNA transfer in forensic science: A review

“…In contrast, van den Berge et al [104] found that the average persistence rates of DNA from both blood and saliva-stained cloths after washing were less than 0.001%, and the transfer of DNA from these stains onto the co-washed items was found to be extremely limited with only a very few alleles, if any, being detected. Whilst Kulstein and Wiegand [191] also obtained no reportable or informative DNA profiles from clean cloths washed with salivastained cloths, they found 52% of saliva-stained cloths gave reportable DNA profiles after washing. The reason for such different results between the studies is unclear, especially given that the starting volumes of blood and saliva in Kulstein and Wiegand's study were smaller than those used by van den Berge et al (20/100 µl versus 500/1000 µl).…”

“…For example, DNA profiles from semen stains were found to still be retrievable after washing and also retrievable from other co-washed clothing as well as the washing machine drum [161,189]. Similarly, reportable and/or informative DNA profiles from blood tended to be obtained from washed blood-stained cloths and from co-washed clean cloths [190][191][192]. In contrast, van den Berge et al [104] found that the average persistence rates of DNA from both blood and saliva-stained cloths after washing were less than 0.001%, and the transfer of DNA from these stains onto the co-washed items was found to be extremely limited with only a very few alleles, if any, being detected.…”