Plenary Sessions

Roland van Oorschot (Australia)

• Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, Australia
• School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Australia

The discovery, 30 years ago, that DNA profiles can be generated from "touched" surfaces has had a major impact on the use of DNA in investigations of alleged criminal activities. By broadening the types of objects and surfaces from which useful DNA could be recovered, and by expanding the types of criminal offences for which DNA sampling and analysis could be of assistance, the capacity of the legal fraternity to arbitrate during legal proceedings has strengthened.

However, these advances also brought several challenges. Some practitioners were initially reluctant to accept this discovery, and many laboratories had to adjust their workforce and practices to accommodate an increase in samples and new workflows. Operationally, laboratories faced the need to optimise DNA targeting, collection and recovery methods while also investing in reducing contamination risks. Simultaneously, greater attention was required to understand the dynamics and variables influencing direct and indirect transfer, persistence and prevalence of DNA. The increasing complexity of mixtures encountered added further difficulties. In addition, there remained limited availability of relevant probability data on types of DNA profiles recovered after a wide range of activity level related scenarios hindering activity level evaluations (ALE). Importantly, the field required development of sound methodologies to conduct ALE, training of staff to build expertise and coordinated efforts with the legal community to ensure the appropriate and timely use of these evaluations.

This presentation will provide some reflections on: circumstances associated with the initial discovery; the journey of advancing the knowledge, awareness and utilities of DNA Transfer, Persistence, Prevalence and Recovery (DNA‑TPPR); some relevant current DNA‑TPPR research activities; and aspects requiring further efforts to enhance the utilisations of "touch" related samples.

Wojciech Branicki (Poland)

Inferring distinctive traits from DNA, especially those relating to externally visible characteristics, can speed up the process of human identification. While biogeographic ancestry can provide insights into physical appearance, the most comprehensive and accurate description of an unknown individual can be achieved through the DNA-based prediction of physical traits. 

Basic research studies have made significant progress in explaining the heritability of many appearance traits, and growing datasets are providing an increasing insight into the role of rare DNA variants in predicting phenotypes. The most anticipated, yet also the most challenging, is the prediction of distinctive facial morphology traits. 

Progress in the field of forensic epigenetic profiling has delivered robust new tools for accurate age estimation across various tissues and cell types and is developing towards maximal accuracy, also in legal age estimation cases. However, the potential of epigenetic profiling is much greater. DNA methylation patterns contain complementary information for predicting appearance, but more broadly, they can be used to create a complete profile of an individual, which may include information about their lifestyle and environmental exposures. The methylome is also being investigated as a potential source of markers to differentiate between monozygotic twins. 

Methods of forensic DNA intelligence that rely on phenotyping and epigenetic profiling can make a significant contribution to solving criminal and DVI cases. Ultimately, optimal sequencing technology is essential for examining various types of markers to a high standard in typical forensic scenarios. 

Chantal Frégeau (Canada)

Since its adoption within the Canadian justice investigative landscape in 1989, DNA typing analysis has evolved quickly to allow processing of ever more minute and/or compromised biological samples associated with crime scenes, missing persons cases and mass disasters. Improvements to these initial DNA-based technologies logically led to the identification of robust genetic markers via collaborative work between Canada, the US and the UK. These markers, when combined with highly sensitive detection methods, revolutionized forensic human identification in the mid-1990’s and were eventually included into STR megaplexes used worldwide today.

Thereafter, the development of automated processes in 1999 for the analysis of convicted offender samples was instrumental to the establishment of the National DNA Data Bank (NDDB) which opened in 2000. Further refinements in robotics allowed processing of Break and Enter samples in 2003 and all crime scene samples submitted to the Royal Canadian Mounted Police National Forensic Laboratory Services since 2005. Significant increases in case processing efficiency were gained in the Canadian forensic laboratories by the implementation of automated processes.

The inclusion of lineage markers (mitochondrial and Y) to the genetic tools assisted with missing persons cases and sexual assault cases. More recently, sequencing-based technologies and SNP-based markers are being considered or used to provide additional genetic information.

This presentation will highlight contributions made by the forensic community (federal and provincial forensic laboratories) in Canada to the forensic DNA typing analysis pipelines and will showcase some of the noteworthy criminal and disaster victim identification cases solved by these various DNA technologies.

Christi Guerrini (USA)

Investigative genetic genealogy (IGG) has transformed forensic human identification since its public debut in 2018, helping to close hundreds of cases involving violent crimes, unidentified human remains, and wrongful convictions. Yet IGG's power rests on a distinct set of ethical tensions and social conditions and still-nascent policy foundations.

This presentation will synthesize the empirical and normative research on the ethical, legal, and social implications of IGG. It will begin with the foundational ethical questions that accompanied IGG's emergence, with a focus on privacy and consent. It will then turn to empirical research on public attitudes and perspectives.

Survey and focus group data reveal broad public support across a wide range of IGG applications, suggesting that context and purpose shape privacy preferences. However, support is vulnerable to misconceptions about IGG that circulate in public discourse.

The presentation will conclude with consideration of the policy landscape, drawing on findings from a surveillance study of IGG policies and U.S. state data privacy statutes. Together, this body of research points toward a future agenda for the field that includes critical attention to:

• issues of database dependency,
• responsible public communication,
• the development of governance frameworks that will keep pace with IGG's growing reach.

Leonor Gusmão (Brazil)

This presentation will describe the main aspects of population genetics that support forensic practice. Population genetics provides the statistical basis for a robust interpretation of genetic evidence in forensic genetics. Central to the forensic field is the characterization of allelic/haplotypic frequency distributions and population structure, which supports the calculation of matching probabilities and likelihood ratios for both recombining and non-recombining markers.

Advances in the study of genetic variation and its population distribution patterns have strengthened applications in human identification, complex kinship analysis, and inference of maternal and paternal lineages. Understanding population diversity has also contributed to improved modeling of mutation processes, particularly for microsatellites, refining statistical assessments in kinship testing. Knowledge of population history has also proven relevant in the interpretation of forensic cases involving specific populations.

The reconstruction of demographic events that shape the distribution of alleles/haplotypes in populations has played an important role in understanding population substructure, particularly for regions shaped by recent and complex demographic histories. Advances in population genetics applied to forensic science have increased the accuracy of statistical inferences related to the strength of evidence, enabling methodological innovations in kinship inference, probabilistic interpretation of genetic mixtures, and assessment of allelic/haplotype frequency uncertainty, reinforcing its essential role in the resolution of forensic cases.

Despite this, population genetics applied to forensic science still faces several challenges. There is still a lack of representativeness of population data for some countries, hindering robust statistical inferences. This heterogeneity of representativeness worldwide has been further aggravated by rapid technological advances, including an increasingly wide range of markers, which in complex cases involving samples with low amounts of genetic material, mixtures, or closely related individuals, further overburden existing statistical models. At the same time, ethical and legal concerns related to privacy, proportionality, and communication of probabilistic results have been raised, highlighting the importance of clear and careful ethical practices in the application of population genetics to forensics.

Michael Marciano (USA)

Resolving mixtures remains one of the most significant challenges in forensic DNA analysis. The advent of probabilistic genotyping methods have been instrumental in addressing these challenges however these systems use mathematical and statistical modeling to probabilistically deconvolute profiles. Instead, envision a world unburdened by mixed profiles and statistical uncertainty; this is the story of how recent advances in single cell analyses in forensic science have evolved to become a new multifaceted tool to reduce complexity and provide the highest profile resolution possible.

Single cell analysis has long been a focus outside of the forensic community, with innovative instruments and techniques being developed at a rapid pace. However, the forensic DNA field has yet to take full advantage of this powerful analysis. In addition, single cell analyses can offer more than improvements in the resolution of mixtures, meeting other significant needs in the forensic community. For example, the ability to link the DNA profile with cell type and help inform low quantity bulk sample interpretation.

However, it is not without challenges, namely, cell recovery methods suitable for forensic use, throughput, and inherent stochastic effects (i.e., Will enough information be present to make conclusions?). These challenges have been or are currently being addressed. 

This presentation will provide a historical overview of single cell analysis and highlight recent advances including several studies that provide perspective into methods, expected results, advantages/disadvantages and the transition of these analyses from research to the forensic laboratory. These studies include: an overarching view of how modern technologies coupled with slight modifications to the standard workflow can impact profile quality and the information content that can be obtained from single cells; a method to target and recover male epithelial cells from a mixture of female like-cells; the first perspective into the dynamics of stutter on single-copy genomes and the implications on bulk analysis; and preliminary data related to single cell amplicon and whole genome sequencing. Collectively, these studies demonstrate that single cell analysis can be successfully used and implemented in a forensic setting, providing significant advantages over current methods in many situations encountered in casework.