Since the late 1980s forensic DNA typing has undoubtedly been developed as a powerful tool in police investigations for identifying perpetrators of crime or missing persons, via the analysis of autosomal, Y-chromosome or mitochondrial DNA markers. But is this all that we can expect from forensic genetic testing? Certainly not!
As a result of vast scientific and technological advancements over the last few years, the field of forensic genetics is developing fast. Hence, we expect that a wide range of new methods and technologies will soon be added to the next-generation forensic DNA toolkit. Which are these methods?
The panel discussion at ISHI 30, led by Athina Vidaki of Erasmus University Medical Center, will feature highly recognized experts who will present some of the most promising forensic science topics and technologies likely to be introduced in the coming years; more specifically in the fields of microbial forensics, forensically relevant body fluid/tissue identification, forensic DNA phenotyping and genetic genealogy.
written by Athina Vidaki, Erasmus University Medical Center
Firstly, microbial communities can reveal answers to important questions risen during forensic investigations; for example, by examining microbial succession during the decomposition of a dead body we can estimate the time since death, in others words the post-mortem interval. How accurate is this microbial clock of death?
Researchers at Colorado Mesa University are looking to prove that microbes are predictably found at certain times during the decomposition process. Doing so would allow crime scene investigators to rely on this “microbial clock” to help estimate time of death, and potentially the cause.
Currently, investigators rely on the postmortem interval, or estimates of the time since death, to begin to determine what happened to a victim and to authenticate a potential suspect’s alibi. Factors contributing to the postmortem interval include activity on the victim’s credit card, when they were last seen alive, and the state of the body. In certain cases, insect species found on the body can be a clue as well, but it’s not possible to rely on insects alone.
The term “microbial clock” originated from Jessica Metcalf, a microbial ecologist and evolutionary biologist at Colorado State University who leads the FIRS project. In 2010, she decided to shift from using DNA to study Ice Age mammals to working with ancient humans, specifically understanding their gut microbes by studying feces.
During her research, Metcalf thought it wise to gain knowledge on the microbes involved in decomposition. In a study completed in 2013, Metcalf was able to show that microbial successions were consistent across different human bodies and different seasons, even when accounting for seasonal temperatures. Metcalf’s work should allow forensic investigators to uncover how long ago a person had died, to within two to four days, by swabbing and sequencing the microbes that exist on and around the body.
Also, forensic transcriptomics have shown great capacity to reveal tissue-specific patterns, that can be used to provide valuable ‘source level’ information for the police. Can the issue of inter-individual gene expression variation be solved by the inclusion of more tissue-specific mRNA markers in targeted messenger RNA-based sequencing methods?
Furthermore, the panelists will discuss the application of massively parallel sequencing for developing next-generation forensic tools, for example for the combined and high-resolution appearance and ancestry prediction. We will also explore the recent application of epigenetics for estimating one’s chronological age in tissues like blood. How far are we from a complete picture of an unknown individual?
In an interview with ISHI, Walther Parson, a member of VISAGE (Visual Attributes Through Genomics) project explained, “Currently, the most promising forensically relevant predictors are appearance, ancestry and age. These have been developed, investigated and interpreted in the past 10 years using different technologies. VISAGE aims at combining these and harmonizing technologies and interpretation. The main technological platforms are based on Massively Parallel Sequencing (MPS).”
These tools are on the horizon for forensic laboratories. Walther continues, “VISAGE is developing and validating two sets of molecular tools, the basic and the enhanced tools. The former consists of known and mostly published markers and will become available in 2019, the latter includes new markers and is scheduled to become available in 2020.”
Lastly, although its precursor – familial DNA searching – has been successfully used since 2003, forensic ‘genealogics’ has recently been in the public spotlight due to its controversial use of public genetic databases. Long-range familial searches from databases holding millions of DNA profiles can be powerful by providing the missing link in high-profile cold cases like the recent arrest of the alleged Golden State Killer. But what about the extensive potential privacy invasions – are we all under scrutiny?
How have the aforementioned tools been developed and what are the prerequisites for their accurate use and interpretation? Despite their high potential, bringing these new forensic science technologies into the justice system will entail overcoming a wide range of scientific, technological, investigative, ethical and legal challenges. During this panel discussion our experts will share more about these topics and the wider picture of what the future holds for forensics. You don’t want to miss it!
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