Investigation into Normal Background DNA on Adult Necks: Implications for DNA Profiling of Manual Strangulation Victims

Graham, Eleanor and Rutty, Guy (2008) Investigation into Normal Background DNA on Adult Necks: Implications for DNA Profiling of Manual Strangulation Victims. Journal of Forensic Sciences, 53 (5). pp. 1074-1082. ISSN 0022-1198

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Abstract

Others have investigated the role that DNA profiling could play as a method for identifying the perpetrator of manual strangulation. These studies have demonstrated that it is possible to collect offender DNA from the skin surface of a victim following physical contact. It is not known whether nonself biological material is normally present on the skin surface due to adventitious transfer occurring during innocent everyday interactions. To test the hypothesis that detectable amounts of nonself DNA are normally present on the skin surface of healthy adult individuals due to the adventitious transfer of DNA occurring during normal day-to-day social interactions, we designed an experiment in three phases. Phase 1 was used to deduce which DNA collection, extraction, and amplification methods were suited to investigating this question. During phase 2, the neck surface of 24 healthy adult volunteers was swabbed. DNA was extracted using the QIAamp DNA mini kit and amplified using the SGM Plus PCR amplification kit, using 28 PCR cycles. The work carried out during phase 3 involved a simulated assault to investigate primary and secondary transfer of DNA during physical contact. It was found that 23% of neck areas swabbed during phase 2 of this investigation showed nondonor alleles in the resulting DNA profile, with 5% of areas showing six or more nondonor alleles. The results of phase 3 showed that primary, secondary, and zero transfer of victim and/or offender DNA could be observed after physical contact and that alleles from an unknown source could still be detected in this more controlled experiment. The data presented in this paper demonstrate that DNA profiles generated after swabbing the skin surface of healthy adults can include components of an unknown source, present due to adventitious transfer. These components, if present in large quantities, have the potential to interfere with DNA profile interpretation of swabs taken for the investigation of physical assault by DNA profiling.

Item Type:	Article
Uncontrolled Keywords:	forensic science, DNA, strangulation, manual, normal, offender, victim
Subjects:	B100 Anatomy, Physiology and Pathology C700 Molecular Biology, Biophysics and Biochemistry F400 Forensic and Archaeological Science
Department:	Faculties > Health and Life Sciences > Applied Sciences
Depositing User:	Ay Okpokam
Date Deposited:	20 Dec 2011 09:19
Last Modified:	12 Oct 2019 17:31
URI:	http://nrl.northumbria.ac.uk/id/eprint/4289

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