title: The origin of unknown source DNA from touched objects.
abstract: The presence of DNA in a criminal investigation often requires scrutiny in relation to how it came to be where it was found. There is a paucity of data with respect to the extent to which one can assume that the last person handling an object, which has previously been touched by others, will contribute to the DNA profile generated from it. There are limited data in detailing the extent to which any foreign DNA is picked-up from a previously touched object and transferred to subsequently touched objects. This study focuses on DNA transfer and persistence on a knife handle after multiple handlings with the knife by different individuals soon after each other, as well as handprints left on flat DNA-free surfaces immediately after touching a knife handle with a known history of prior handling. The profiles of later handlers of a knife are more prominent than earlier handlers; however, the last handler is not always the major contributor to the profile. Proportional contributions to the profiles retrieved from knife handles vary depending on the individuals touching the knife handle. They can also vary when knife handles have been handled in the same manner by the same individuals in the same sequence on different occasions. Hands readily pickup DNA left on objects by others and transfer it to subsequently touched objects. The quantity of foreign DNA picked up by a hand and deposited on subsequently touched objects diminishes as more DNA-free objects are handled soon after each other. Caution is advised when considering how DNA from different individuals may have been transferred to the object from which it was collected.
authors: Deakin University, School of Life and Environmental Sciences, Centre for Chemistry and Biotechnology, (Waurn Ponds Campus), 75 Pigdons Road, Locked Bag 20000, Geelong, Victoria 3217, Australia; Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, Victoria 3085, Australia. Electronic address: Alycia.BUCKINGHAM@police.vic.gov.au.
authors: Alycia K
authors: AK
authors: Buckingham
authors: Deakin University, School of Life and Environmental Sciences, Centre for Chemistry and Biotechnology, (Waurn Ponds Campus), 75 Pigdons Road, Locked Bag 20000, Geelong, Victoria 3217, Australia.
authors: Michelle L
authors: ML
authors: Harvey
authors: Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, Victoria 3085, Australia.
authors: Roland A H
authors: RAH
authors: van Oorschot
mesh_terms: D004247:DNA / Q000235:genetics / Q000302:isolation & purification*; D016172:DNA Fingerprinting; D006801:Humans; D013048:Specimen Handling; D014110:Touch
chemical_list: D004247:DNA
keywords: DNA transfer; Knife handle; Non-self DNA; Touch DNA; Trace DNA