Collection techniques of Touch DNA deposited on human skin following a strangulation scenario

Abstract

Trace DNA is a significant type of evidence for its ability to be collected from touched items or surfaces at crime scenes to link suspects to their crimes. In cases of violent crimes like assault, sexual offences, or even homicide, often touch DNA is collected from the victim’s skin. However, the collection of Touch DNA from the victim's skin can be complex because of the mixture of DNA present, as there is likely to be a small quantity of the offender’s DNA compared to the victim’s DNA. Validating different collection methods or techniques can improve Touch DNA sampling, therefore, this study investigated three collection techniques involving cotton and nylon swabs to test their efficiency for the collection of touch DNA from the human neck. There was a significant difference between the three recovery techniques used to recover Touch DNA with a cotton swab (CS) (p < 0.05) and nylon swab (NS) (p < 0.05), with more alleles observed when the neck skin was moistened with 100 µl of distilled water using spray a bottle before collection for both swabs.