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Abstract

Wearer DNA is the deposit of epithelial cells on clothing worn by an individual. Detection of the last individual to handle or wear an item is often an important and desirable determination in forensic science. The most commonly used collection methods for wearer DNA include swabbing and scraping. These often result in mixture profiles. Recently, adhesives have been introduced as a possible reliable method for the collection of biological evidence. The goal of the research was to compare the current collection methods of swabbing and scraping with a gel film called Gel-Pak ‘0’ which shares similar properties with adhesives. Gel-Pak ‘0’ has been previously studied in comparison to other adhesives for the collection of epithelial cells, and was shown to recover the top layer of loose particulate. This particulate had a tendency to be deposited by the individual who last came in contact with an item. Therefore, in comparison to the other two collection methods, Gel-Pak ‘0’ was

hypothesized to recover single source profiles on clothing items from the most recent wearer. DNA analysis was performed on samples collected by the three methods from various clothing items including baseball hats, t-shirts, sweatpants, socks, and other items commonly submitted to crime labs for DNA analysis. The habitual wearer and the second/last wearer wore each item for a predetermined amount of time. The results of the research showed that Gel-Pak ‘0’ recovered a similar number of CODIS (local and national) eligible profiles as swabbing. However, coupled with the fact that it is time consuming, costly, and cannot be used on all surfaces, Gel-Pak ‘0’ was determined to not make for an effective collection method of the most recent wearer’s DNA. Therefore, Gel-Pak ‘0’ will not be considered for casework. Although Gel-Pak ‘0’ will not be further used, the results did reveal some trends that may shed light on how DNA analysts may approach wearer DNA cases. Swabbing had a tendency to yield smaller amounts of DNA in comparison to scraping, but obtain DNA from the last wearer of the piece of clothing more effectively than the other two methods. Scraping had a tendency to yield greater quantities of DNA, recovering more DNA from the habitual wearer due to its invasive nature. Revealing individuals who last wore an item can be of great importance in forensic science, and therefore, further research with various adhesives and gel films could be vital for solving forensic investigations.

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