DNA Transfer in Forensic Science: Recent Progress towards Meeting Challenges

Abstract

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.

A Logical Framework for Forensic DNA Interpretation

“…It would ensure DNA scientists adhere to the principles of interpretation as advocated in the Forensic Science Regulator of England and Wales codes of practice and conduct for evaluative opinions [ 12 ]. We note also that in some countries, such as the Netherlands, there have been initiatives by The Netherlands Register of Court Experts [ 76 , 77 ] to guarantee and promote the quality of the contribution made by court experts to the legal process. This is an avenue other countries could pursue to ensure that experts are fully qualified and certified for both types of reporting.…”

Recent advances in forensic biology and forensic DNA typing: INTERPOL review 2019–2022

“…To evaluate DNA findings given activity-level propositions it is important to understand the factors and variables that may impact DNA transfer, persistence, prevalence, and recovery (DNA-TPPR). These factors include history of contacting surfaces, biological material type, quantity and quality of DNA, dryness of biological material, manner and duration of contact, number and order of contacts, substrate type(s), time lapses and environment, and methods and thresholds used in the forensic DNA laboratory to generate the available data [ 297 ].…”

“…Three valuable review articles were published on this topic in 2019 [ 14 , 28 , 299 ]. Following a comprehensive January 2019 review that cited [ 298 ] references on DNA-TPPR [ 14 ], the same authors provided an update in November 2021 on recent progress towards meeting challenges and a synopsis of 144 relevant articles published between January 2018 and March 2021 [ 297 ]. While few studies provide the information needed to help assign probabilities of obtaining DNA results given specific sets of circumstances, progress includes use of Bayesian Networks [ 300 ] to identify variables for complex transfer scenarios [ 38 , [301] , [302] , [303] , [304] , [305] ] as well as development of an online database DNA-TrAC 43 for relevant research articles [ 299 ] and a structured knowledge base 44 with information to help practitioners interpret general transfer events at an activity level [ 306 ].…”

Assessing the use of environmental DNA (eDNA) as a tool in the detection of human DNA in water

“…Recent improvements in the ability to detect, collect, and genotype trace quantities of DNA have assisted many forensic investigations [ 1 , 2 , 3 ]. The utilization of environmental DNA (eDNA) as a tool in detecting human DNA may provide additional opportunities for the collection of evidence to assist forensic investigations.…”