A review of trace “Touch DNA” deposits: Variability factors and an exploration of cellular composition

Abstract

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Open source software tool for the automated detection and characterization of epithelial cells from trace biological samples

“…This observation that trace cell 6 populations from certain individuals may have distinct morphological and/or structural properties is consistent with previous studies (9,14). Additionally, although contributor-specific trends in the deposition of cellular material and DNA have been observed (2,4), the propensity of individuals to systematically deposit more or less DNA in a touch/contact sample (i.e., shedder status) remains the subject of significant debate within the forensic community (7). This workflow which can quantify fluorescence on a per cell basis after treatment with a DNA-specific dye can therefore potentially be used to experimentally test hypotheses around shedder status and elucidate biological mechanisms governing the deposition, transfer, and persistence of trace DNA in forensic samples.…”

“…Although there are several software tools for the unsupervised recognition and segmentation of cells from microscopic images, most rely on nuclear staining and/or counterstaining of different cellular constituents. For touch/contact cell populations, a vast majority of cells are likely to be anucleate and to have limited amounts of both intracellular DNA and other traditional targets for fluorescent probes (7,8). This may limit the effectiveness of existing detection methods.…”

DNA detection of a temporary and original user of an office space

“…The use of DNA profiles from touched items/surfaces has also raised the need to acquire a good understanding of issues relating to DNA persistence and transfer [4,7]. Improved knowledge in this area will assist in addressing frequently posed questions regarding activities of interest, such as those relating to the probability of detecting the last person who touched an item/surface given a particular action and their relative proportion (if not a single source), within any mixed profiles generated from samples collected.…”

Touch DNA: impact of handling time on touch deposit and evaluation of different recovery techniques: An experimental study

“…“Touch DNA” is DNA obtained from shed skin cells and other biological material transferred from a donor to an object or a person during physical contact 1,2 . This particular kind of evidence could play an essential role in forensic laboratory work and is considered an important tool for investigators 3 .…”