Lessons from a study of DNA contaminations from police services and forensic laboratories in Switzerland.

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Version: Author's accepted manuscript
License: CC BY-NC-ND 4.0
Serval ID
serval:BIB_F05DA40ACF83
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Lessons from a study of DNA contaminations from police services and forensic laboratories in Switzerland.
Journal
Forensic science international. Genetics
Author(s)
Basset P., Castella V.
ISSN
1878-0326 (Electronic)
ISSN-L
1872-4973
Publication state
Published
Issued date
03/2018
Peer-reviewed
Oui
Volume
33
Pages
147-154
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
In Switzerland, the DNA profiles of police officers collecting crime scene traces as well as forensic genetic laboratories employees are stored in the staff index of the national DNA database to detect potential contaminations. Our study aimed at making a national inventory of contaminations to better understand their origin and to make recommendations in order to decrease their occurrence. For this purpose, a retrospective questionnaire was sent to both police services and forensic genetic laboratories for each case where there was a contamination. Between 2011 and 2015, a total of 709 contaminations were detected. This represents a mean of 11.5 (9.6-13.4) contaminations per year per 1'000 profiles sent to the Swiss DNA database. Feedbacks were obtained from the police, the laboratory or both for 552/709 (78%) of the contaminations. Approximately 86% of these contaminations originated from police officers whereas only 11% were from genetic laboratories employees and 3% were associated to other sources (e.g. positive controls, stain-stain contaminations). Interestingly, a direct contact between the stain and the contaminant person occurred in only 51% of the laboratory contaminations whereas this number increased to 91% for police collaborators. The high level of indirect DNA transfer in laboratories might be explained by the presence of "DNA reservoirs" suggesting that cleaning procedures should be improved. At the police level, most contaminations originated from the person who collected the trace and likely occurred directly at the crime scene. Improving sampling practices could be beneficial to reduce these contaminations.
Keywords
DNA Contamination, Humans, Laboratories/statistics & numerical data, Police/statistics & numerical data, Retrospective Studies, Surveys and Questionnaires, Switzerland, DNA contamination, Forensic DNA analysis, Recommendations, Transfer
Pubmed
Web of science
Open Access
Yes
Create date
08/01/2018 12:43
Last modification date
20/08/2019 17:18
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