- •A survey about DNA contaminations in Switzerland.
- •About 1% of the profile sent to the national database are known to be contaminated.
- •Staff index elimination database allow early detection of contaminations.
- •Most contaminations likely occurred during DNA collection on crime scene.
- •Contamination prevention recommendations are necessary.
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.
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- Error rates in forensic DNA analysis: definition, numbers, impact and communication.Forensic Sci. Int. – Genet. 2014; 12: 77-85
- Contamination during criminal investigation: detecting police contamination and secondary DNA transfer from evidence bags.Forensic Sci. Int. – Genet. 2016; 23: 121-129
- Environmental DNA monitoring: beware of the transition to more sensitive typing methodologies.Aust. J. Forensic Sci. 2013; 45: 323-340
- Leading-edge forensic DNA analyses and the necessity of including crime scene investigators, police officers and technicians in a DNA elimination database.Forensic Sci. Int. – Genet. 2015; 19: 50-55
- Female criminals—it’s not always the offender!.Forensic Sci. Int. Genet. Suppl. Ser. 2009; 2: 145-146
- Contamination when collecting trace evidence – An issue more relevant than ever?.Forensic Sci. Int. Genet. Suppl. Ser. 2015; 5: e603-3604
- Risk of dna transfer by gloves in forensic casework.Forensic Sci. Int. Genet. Suppl. Ser. 2015; 5: E527-E529
- DNA transfer by examination tools – a risk for forensic casework?.Forensic Sci. Int. – Genet. 2015; 16: 246-254
- Trace DNA presence, origin, and transfer within a forensic biology laboratory and its potential effect on casework.J. Forensic Ident. 2006; 56: 558-576
- Beware of the possibility of fingerprinting techniques transferring DNA.J. Forensic Sci. 2005; 50: 1417-1422
- Assessment of the possibility of DNA accumulation and transfer in a superglue chamber: a preliminary study.J. Forensic Ident. 2012; 62: 409-424
- Ordonnance du DFJP sur les exigences de prestations et de qualité requises pour les laboratoires forensiques d’analyse d’ADN.2015
- Forensic errors.Criminal Law Justice Weekly. 2017; 181
- Inquiry into the Circumstances That Led to the Conviction of Mr Farah Abdulkadir Jama.Victorian Government printer, 2010
- DIP–STR: A new marker for resolving unbalanced DNA mixtures.Forensic Sci. Int.: Genet. Suppl. Ser. 2011; 3: e1-e2
- DIP-STR: highly sensitive markers for the analysis of unbalanced genomic mixtures.Hum. Mutat. 2013; 34: 644-654
- DNA transfer: review and implications for casework.Forensic Sci. Int. – Genet. 2013; 7: 434-443
- Secondary and subsequent DNA transfer during criminal investigation.Forensic Sci. Int. – Genet. 2015; 17: 155-162
- The effectiveness of protective clothing in the reduction of potential DNA contamination of the scene of crime.Int. J. Legal Med. 2003; 117: 170-174
- Observations of DNA transfer within an operational forensic biology laboratory.Forensic Sci. Int. – Genet. 2016; 23: 33-49
- Considerations relating to the components of a laboratory DNA contamination minimisation monitoring (DCMM) program.Forensic Sci. Policy Manage.: Int. J. 2015; 6: 91-105
- DNA contamination minimisation –finding an effective cleaning method.Aust. J. Forensic Sci. 2015; 47: 428-439
- Contamination Prevention Guidelines.2010
- The Control and Avoidance of Contamination in Laboratory Activities Involoving DNA Evidence Recovery and Analysis.2016 (Crown Copyright)
- DNA Anti-Contamination –Forensic Medical Examination in Sexual Assault Referral Centres and Custodial Facilities.2016 (Crown copyright)
- The Control and Avoidance of Contamination In Crime Scene Examination Involving DNA Evidence Recovery.2016 (Crown Copyright)
Published online: December 19, 2017
Accepted: December 19, 2017
Received in revised form: November 16, 2017
Received: August 21, 2017
© 2017 Elsevier B.V. All rights reserved.