Jaarlijks stellen forensisch rechercheurs van de politie ongeveer 27.000 biologische sporen veilig die ze doorsturen naar het Nederlands Forensisch Instituut (NFI) voor DNA-onderzoek (Kruize & Gruter2018). Deze onderzoeken worden aangevraagd vanuit de verwachtingdat dit DNA-onderzoek kan bijdragen aan de opsporing en bewijsvoering van strafzaken. In dit artikel zal ik eerst beschrijven wat DNA-onderzoek zo interessant maakt voor de opsporing en bewijsvoeringvan strafzaken. Voorts zal ik ingaan op de knelpunten die zich momenteel voordoen in het forensisch DNA-onderzoek, en die maken dat forensisch DNA-onderzoek nog niet de rol speelt in het opsporingsproces die er gezien de technische mogelijkheden van kan worden verwacht. Voorts richt ik me op de mogelijkheden om deze knelpunten in de nabije toekomst met nieuwe wetenschappelijke inzichten en met nieuwe technieken op te lossen. Ik concentreer me in dit artikel op vier aspecten van het forensische opsporingsproces, namelijk (1) het vinden van biologische sporen, (2) het bepalen van de relevantie en de succeskans van de aangetroffen biologische sporen, (3) het leerproces van rechercheurs, en (4) het belang van de integratie van processen die nu door verschillende professionals op verschillende plaatsen worden verricht, en de bevorderende werking van snelle analysemogelijkheden in deze ontwikkeling. Voor informatie over het gebruik van (genealogische) databanken in de opsporing verwijs ik naar het artikel van Meulenbroek en Aben elders in dit nummer; voor informatie over ontwikkelingen ten aanzien van persoonseigenschappen die uit DNA kunnen worden afgeleid, zie Kayser (2015), Matheson (2016) en Xavier e.a. (2020).
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Understanding the factors that may impact the transfer, persistence, prevalence and recovery of DNA (DNA-TPPR), and the availability of data to assign probabilities to DNA quantities and profile types being obtained given particular scenarios and circumstances, is paramount when performing, and giving guidance on, evaluations of DNA findings given activity level propositions (activity level evaluations). In late 2018 and early 2019, three major reviews were published on aspects of DNA-TPPR, with each advocating the need for further research and other actions to support the conduct of DNA-related activity level evaluations. Here, we look at how challenges are being met, primarily by providing a synopsis of DNA-TPPR-related articles published since the conduct of these reviews and briefly exploring some of the actions taken by industry stakeholders towards addressing identified gaps. Much has been carried out in recent years, and efforts continue, to meet the challenges to continually improve the capacity of forensic experts to provide the guidance sought by the judiciary with respect to the transfer of DNA.
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To accelerate differentiation between Staphylococcus aureus and Coagulase Negative Staphylococci (CNS), this study aimed to compare six different DNA extraction methods from 2 commonly used blood culture materials, i.e. BACTEC and Bact/ALERT. Furthermore, we analyzed the effect of reduced blood culture times for detection of Staphylococci directly from blood culture material. A real-time PCR duplex assay was used to compare 6 different DNA isolation protocols on two different blood culture systems. Negative blood culture material was spiked with MRSA. Bacterial DNA was isolated with: automated extractor EasyMAG (3 protocols), automated extractor MagNA Pure LC (LC Microbiology Kit MGrade), a manual kit MolYsis Plus, and a combination between MolYsis Plus and the EasyMAG. The most optimal isolation method was used to evaluate reduced bacterial culture times. Bacterial DNA isolation with the MolYsis Plus kit in combination with the specific B protocol on the EasyMAG resulted in the most sensitive detection of S.aureus, with a detection limit of 10 CFU/ml, in Bact/ALERT material, whereas using BACTEC resulted in a detection limit of 100 CFU/ml. An initial S.aureus load of 1 CFU/ml blood can be detected after 5 hours of culture in Bact/ALERT3D by combining the sensitive isolation method and the tuf LightCycler assay.
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The study of human factors in forensic science informs our understanding of the interaction between humans and the systems they use. The Expert Working Group (EWG) on Human Factors in Forensic DNA Interpretation used a systems approach to conduct a scientific assessment of the effects of human factors on forensic DNA interpretation with the goal of recommending approaches to improve practice and reduce the likelihood and consequence of errors. This effort resulted in 44 recommendations. The EWG designed many of these recommendations to improve the production, interpretation, evaluation, documentation, and communication of DNA comparison results.
MULTIFILE
Artikel over DNA en verjaring.
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Determineren is een belangrijk onderdeel van Integrated Pest Management. Als we niet weten om welk dier het gaat, wetten we niet hoe het leeft, of het schadelijk is en wat we eraan kunnen doen. De meeste determinaties worden aan de hand van uiterlijke kenmerken gedaan, maar er is nog een veelbelovende nieuwe methode: DNA.
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Adhesive tape is a common piece of evidence that can contain a myriad of traces. Due to its adhesive properties, adhesive tape can potentially collect traces unrelated to the crime or relocate crime-relevant traces. This secondary transfer of traces can have crucial implications for the evaluation at the activity level. Therefore, this study investigated the secondary transfer of DNA between layers of adhesive tape and tape and other case- and laboratory-relevant substrates. A drop of diluted blood was deposited on different primary substrates (i.e. duct tape, metal, plastic, textile, nitrile gloves). Subsequently, the primary substrate was brought into contact with a secondary substrate, and DNA was collected from both surfaces to measure transfer rates. The highest transfer rates were detected between the adhesive side of the tape and plastic, whereas the lowest transfer rates were detected between the adhesive side and textile. It was shown that the adhesive readily collects DNA from plastic and nitrile gloves commonly used in the laboratory, which highlights the importance of working with DNA-free materials. Therefore, this study demonstrated the need for caution when interpreting traces on adhesive tapes, always taking possible situations of secondary transfer into account.
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Technological innovations enable rapid DNA analysis implementation possibilities. Concordantly, rapid DNA devices are being used in practice. However, the effects of implementing rapid DNA technologies in the crime scene investigation procedure have only been evaluated to a limited extent. In this study a field experiment was set up comparing 47 real crime scene cases following a rapid DNA analysis procedure outside of the laboratory (decentral), with 50 cases following the regular DNA analysis procedure at the forensic laboratory. The impact on duration of the investigative process, and on the quality of the analyzed trace results (97 blood and 38 saliva traces) was measured. The results of the study show that the duration of the investigation process has been significantly reduced in cases where the decentral rapid DNA procedure was deployed, compared to cases where the regular procedure was used. Most of the delay in the regular process lies in the procedural steps during the police investigation, not in the DNA analysis, which highlights the importance of an effective work process and having sufficient capacity available. This study also shows that rapid DNA techniques are less sensitive than regular DNA analysis equipment. The device used in this study was only to a limited extent suitable for the analysis of saliva traces secured at the crime scene and can mainly be used for the analysis of visible blood traces with an expected high DNA quantity of a single donor.
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Mobile Rapid DNA technology is close to being incorporated into crime scene investigations, with the potential to identify a perpetrator within hours. However, the use of these techniques entails the risk of losing the sample and potential evidence, because the device not only consumes the inserted sample, it is also is less sensitive than traditional technologies used in forensic laboratories. Scene of Crime Officers (SoCOs) therefore will face a ‘time/success rate trade-off’ issue when making a decision to apply this technology.In this study we designed and experimentally tested a Decision Support System (DSS) for the use of Rapid DNA technologies based on Rational Decision Theory (RDT). In a vignette study, where SoCOs had to decide on the use of a Rapid DNA analysis device, participating SoCOs were assigned to either the control group (making decisions under standard conditions), the Success Rate (SR) group (making decisions with additional information on DNA success rates of traces), or the DSS group (making decisions supported by introduction to RDT, including information on DNA success rates of traces).This study provides positive evidence that a systematic approach for decision-making on using Rapid DNA analysis assists SoCOs in the decision to use the rapid device. The results demonstrated that participants using a DSS made different and more transparent decisions on the use of Rapid DNA analysis when different case characteristics were explicitly considered. In the DSS group the decision to apply Rapid DNA analysis was influenced by the factors “time pressure” and “trace characteristics” like DNA success rates. In the SR group, the decisions depended solely on the trace characteristics and in the control group the decisions did not show any systematic differences on crime type or trace characteristic.Guiding complex decisions on the use of Rapid DNA analyses with a DSS could be an important step towards the use of these devices at the crime scene.
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Sinds februari 2023 is het Lectoraat Diversiteitsvraagstukken betrokken bij de ontwikkeling van de Nieuwe Leraren Academie / De Inholland Pabo met als kernopdracht: Onderzoek en adviseer op welke manier inclusiviteit in alle aspecten van De Inholland Pabo verweven kan worden en kan fungeren als een kernprincipe van de aanstaande onderwijsontwikkeling. Kort gezegd en vrij vertaald: Hoe zorgen we ervoor dat inclusief onderwijs deel uitmaakt van het DNA van De Inholland Pabo? In dit rapport kun je de resultaten en aanbevelingen lezen die uit dit onderzoek zijn voortgekomen.
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