Evaluation of forensic genetics findings given activity level propositions: A review.

The evaluation of results of forensic genetic analyses given activity level propositions is an emerging discipline in forensic genetics. Although it is a topic with a long history, it has never been considered to be such a critically important topic for the field, as today. With the increasing sensitivity of analysis techniques, and advances in data interpretation using probabilistic models ('probabilistic genotyping'), there is an increasing demand on forensic biologists to share specialised knowledge to help recipients of expert information address mode and timing of transfer and persistence of traces in court. Scientists thereby have a critical role in the assessment of their findings in the context of the case. This helps the judiciary with activity level inferences in a balanced, robust and transparent way, when based on (1) proper case assessment and interpretation respecting the hierarchy of propositions (supported by, for example, the use of Bayesian networks as graphical models), (2) use of appropriate data to inform probabilities, and (3) reporting guidelines by international bodies. This critical review of current literature shows that with certain prerequisites for training and quality assurance, there is a solid foundation for evidence interpretation when propositions of interest are at the 'activity level'

Resolving riddles and presenting new puzzles in Chonorinidae Phylogenetics

The snails__ proverbial inertness makes it an ideal subject to study the patterns and processes that lead to speciation. The land snail family Chondrinidae consists of about 70 extant species in six genera. They occur throughout western and central Europe, northern Africa and as far east as Pakistan. These snails share a long and interesting evolutionary history, to the knowledge of which we contribute here.LEI Universiteit LeidenEvolutiebiologi

DNA transfer in forensic science: A review

© 2018 Elsevier B.V. Understanding the variables impacting DNA transfer, persistence, prevalence and recovery (DNA-TPPR) has become increasingly relevant in investigations of criminal activities to provide opinion on how the DNA of a person of interest became present within the sample collected. This review considers our current knowledge regarding DNA-TPPR to assist casework investigations of criminal activities. There is a growing amount of information available on DNA-TPPR to inform the relative probabilities of the evidence given alternative scenarios relating to the presence or absence of DNA from a specific person in a collected sample of interest. This information should be used where relevant. However, far more research is still required to better understand the variables impacting DNA-TPPR and to generate more accurate probability estimates of generating particular types of profiles in more casework relevant situations. This review explores means of achieving this. It also notes the need for all those interacting with an item of interest to have an awareness of DNA transfer possibilities post criminal activity, to limit the risk of contamination or loss of DNA. Appropriately trained forensic practitioners are best placed to provide opinion and guidance on the interpretation of profiles at the activity level. However, those requested to provide expert opinion on DNA-related activity level issues are often insufficiently trained to do so. We advocate recognition of DNA activity associated expertise to be distinct from expertise associated with the identification of individuals. This is to be supported by dedicated training, competency testing, authorisation, and regular fit for purpose proficiency testing. The possibilities for experts to report on activity-related issues will increase as our knowledge increases through further research, access to relevant data is enhanced, and tools to assist interpretations are better exploited. Improvement opportunities will be achieved sooner, if more laboratories and agencies accept the need to invest in these aspects as well as the training of practitioners

DNA Transfer in Forensic Science: Recent Progress towards Meeting Challenges.

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

Activity level DNA evidence evaluation: on propositions addressing the actor or the activity

More often than not, the source of DNA traces found at a crime scene is not disputed, but the activity or timing of events that resulted in their transfer is. As a consequence, practitioners are increasingly asked to assign a value to DNA evidence given propositions about activities provided by prosecution and defense counsel. Given that the dispute concerns the nature of the activity that took place or the identity of the actor that carried out the activity, several factors will determine how to formulate the propositions. Determining factors are (1) whether defense claims the crime never took place, (2) whether defense claims someone other than the accused (either an unknown individual or a known person) performed the criminal activity, and (3) whether it is claimed and disputed that the suspect performed an alternative, legitimate activity or has a relation to the victim, the object, or the scene of crime that implies a legitimate interaction. Addressing such propositions using Bayesian networks, we demonstrate the effects of the various proposition sets on the evaluation of the evidence.Criminal Justice: Legitimacy, accountability, and effectivit

Plaats delict-onderzoek met vooruitziende blik: Anticiperen op alternatieve scenario’s tijdens het sporenonderzoek op de plaats delict

Criminal Justice: Legitimacy, accountability, and effectivit

The interpretation of traces found on adhesive tapes

In violent crimes, adhesive tapes such as duct tape are often used by perpetrators e.g. to tie up a victim. In the forensic examination of such tapes many different types of traces can be found, such as finger marks and human biological traces. These traces are first interpreted at source level. However, even when it is certain that a trace was donated by the suspect this does not necessarily mean that he donated the trace while taping the victim, as he could have e.g. used the tape roll from which the pieces came previous to the crime. Therefore, the trace can also be interpreted at activity level. For this, factors such as transfer, persistence and recovery, as well as the position of the trace as it would have been on the original roll have to be taken into consideration. In this study, we have developed a Bayesian network which can aid the forensic practitioner in his interpretation. From a sensitivity analysis, we have concluded that it would be most desirable to set up further studies to determine the most likely positions of DNA on tape rolls if there has only been innocent contact

A probabilistic approach to body fluid typing interpretation: an exploratory study on forensic saliva testing Law

Criminal Justice: Legitimacy, accountability, and effectivit