Contamination when collecting trace evidence—An issue more relevant than ever?

Pickrahn, Ines; Kreindl, Gabriele; Müller, Eva; Dunkelmann, Bettina; Zahrer, Waltraud; Cemper‐Kiesslich, Jan; Neuhuber, Franz

doi:10.1016/j.fsigss.2015.09.238

Cited by 5 publications

(4 citation statements)

References 2 publications

(2 reference statements)

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“…Although the comparison among the few studies which addressed the frequency of contaminations is difficult (e.g. the definition of the contaminations is not always the same), the frequency of 1% reported here is similar to those reported in recent years studies in Norway and Austria [2,6] but approximately one order of magnitude larger than the frequency reported in a study in Québec (31 cases among ~ 31'000 profiles ≈ 0.1%) [4]. This difference may find an explanation in the higher number of profiles of police collaborators and laboratory employees present in the staff index within the national database in Switzerland (2457) compared to the Québec study (327).…”

Section: Examples Of Explanations Given About Contaminationssupporting

confidence: 84%

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

Basset

Castella

2018

Forensic Science International: Genetics

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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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Section: Examples Of Explanations Given About Contaminationssupporting

confidence: 84%

“…Although several recent studies tried to list and evaluate the occurrence of contaminations (e.g. [1,2,4,6]) or focus on specific modes of contaminations (e.g. [7][8][9][10][11]), few studies tried to address contaminations from both the police and laboratory perspectives.…”

Section: Introductionmentioning

confidence: 99%

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

Basset

Castella

2018

Forensic Science International: Genetics

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“…Despite increased attention, and due to the development of more and more sensitive DNA analysis, alternative scenarios are always represented, involving DNA transfer through a secondary person or medium. The minute amount of a few cells or DNA molecules, which may be applicable for amplification, is not recognizable typically in an autopsy environment and is easily transferable between cases [4,117,118]. Although methodological developments are continuously making efforts to eliminate the effect of contamination artifacts from the profiling process [119,120], less appropriate autopsy sampling, incorporating the undetected contamination incidents, can lead to false interpretation within a DNA laboratory [5].…”

Section: Discussionmentioning

confidence: 99%

Most Common Medico-Legal Autopsy-Related Human and Nonhuman Biological Samples for DNA Analysis

Pádár¹,

Zenke²,

Kozma³

2018

Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis

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The identification and individualization of biological evidences is crucial to actual criminal investigations. In spite of the differences at the national level, all the legal processes attribute particular importance to forensic DNA analysis. However, none of the qualified results from any professional laboratory can produce substantive, valuable evidence with insufficient quality of samples and/or problems with provision of a pristine and controlled environment. The methodology and efficiency of sampling are distinct in case of living persons and in medico-legal autopsy and crime scenes. This chapter is a short overview from the basic introductory information up to ongoing research, and in accordance with constraints on the chapter size, it briefly discusses the important topics of sample collection at medico-legal autopsy for DNA analysis. The content sorts the major types of samples, reviews the common methods of sampling and the potential risk of poor sampling or contamination transfer. The corpses can be more or less degraded, which in special cases (e.g., paraffin embedded tissues, drowned, burning and/or buried cadaver) allow only for analysis of highly degraded samples. The samples can be associated with tissues of a corpse (e.g., blood, soft tissues, bone, tooth, hair) and/or additional extraneous tissues and remains, which are often mixed (e.g., blood, saliva, semen, vaginal fluid, debris of fingernails) on the corpse.

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“…[24] One effective strategy to overcome database contamination is the establishment of elimination databases, which can be crosschecked to eliminate unwanted DNA data. [58][59][60][61] Another strategy is routine integrity checks of loaded DNA data. [34] The presence of unwanted profiles on the database can mislead the police or delay the resolution of cases.…”

Section: Challenges Of the Pofa Implementationmentioning

confidence: 99%

The UK National DNA Database: Implementation of the Protection of Freedoms Act 2012

Amankwaa

McCartney²

2018

Forensic Science International

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In 2008, the European Court of Human Rights, in S and Marper v the United Kingdom, ruled that a retention regime that permits the indefinite retention of DNA records of both convicted and non-convicted ("innocent") individuals is disproportionate. The court noted that there was inadequate evidence to justify the retention of DNA records of the innocent. Since the Marper ruling, the laws governing the taking, use, and retention of forensic DNA in England and Wales have changed with the enactment of the Protection of Freedoms Act 2012 (PoFA). This Act, put briefly, permits the indefinite retention of DNA profiles of most convicted individuals and temporal retention for some first-time convicted minors and innocent individuals on the National DNA Database (NDNAD). The PoFA regime was implemented in October 2013. This paper examines ten post-implementation reports of the NDNAD Strategy Board (3), the NDNAD Ethics Group (3) and the Office of the Biometrics Commissioner (OBC) (4). Overall, the reports highlight a considerable improvement in the performance of the database, with a current match rate of 63.3%. Further, the new regime has strengthened the genetic privacy protection of UK citizens. The OBC reports detail implementation challenges ranging from technical, legal and procedural issues to sufficient understanding of the requirements of PoFA by police forces. Risks highlighted in these reports include the deletion of some "retainable" profiles, which could potentially lead to future crimes going undetected. A further risk is the illegal retention of some profiles from innocent individuals, which may lead to privacy issues and legal challenges. In conclusion, the PoFA regime appears to be working well, however, critical research is still needed to evaluate its overall efficacy compared to other retention regimes.

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Contamination when collecting trace evidence—An issue more relevant than ever?

Cited by 5 publications

References 2 publications

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

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

Most Common Medico-Legal Autopsy-Related Human and Nonhuman Biological Samples for DNA Analysis

The UK National DNA Database: Implementation of the Protection of Freedoms Act 2012

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