Forensic Scientist Jane Taupin discusses the widening net which law enforcement authorities can cast over DNA databases when investigating crime. Recipients of ancestry DNA kits this Christmas should be wary because one’s genetic privacy might not be quite what it seems, she writes. Jane will present on the topic of forensic DNA at the Legalwise March CPD Seminar for Criminal Practitioners. She previously presented on DNA and Crime: Current Issues at Trial.
The arrest of the alleged ‘Golden State Killer’ in the USA in April this year highlighted the expanding reach of police investigative techniques using DNA technology. The legislation of ‘familial DNA searching’ in many jurisdiction (including Australia), where people become suspects for no other reason other than that they are related to a person on a police DNA database, foreshadowed this expansion.
During the mid 1970s to the 1980s in California a series of rapes and murders were attributed to an unknown male individual known variously as the Golden State Killer, the East Area Rapist, the Diamond Knot Killer and the Visalia Ransacker. The case went cold, but during April this year police arrested a suspect, 72 year old Joseph James DeAngelo, a retired police officer. A genetic genealogy website GEDMatch, promoted as an open access site for the public to trace their family history, was searched by police against a crime scene sample obtained from one of the offences (1, 2). The full details of the investigation have not yet been revealed but since this date, there have been many more uses of this technology in the USA, which has raised privacy and ethical concerns. The technique is now known as “long range (or extended) familial searching”.
The new technology
‘Ancestry’ or genetic genealogy websites use a combination of family trees and DNA technology as a tool to trace family members of ‘customers’. The main purpose is to track down birth parents, sperm donors and long lost family, although some promote dubious claims of determining racial or even country of heritage for a specific person. Humans are from the one race and are all related, it is just a matter of degree (see for example 3).
Genealogists can connect family trees using census records, newspaper obituaries and other public records. Companies using DNA technology request a mouth swab from which DNA is extracted in the form of SNPs, or single nucleotide polymorphisms, a type of code in the form of numbers across hundreds of sites on the human genome. SNPs are also used in biomedical studies.
GEDmatch does not offer DNA tests itself but allows uploads of raw data files (using SNPs) from websites that do – such as AncestryDNA, 23andMe, and MyHeritage. It appears that investigators analysed a crime scene sample from 1980 using SNPs and then uploaded the profile under a fake name. DeAngelo was not on GEDmatch but a family tree was built from the uploaded crime scene profile and investigators screened hundreds if not thousands of people. GEDmatch has updated its terms of service to note that law enforcement may be searching through it (4).
The DNA databases used by police focus on up to 20 DNA sites of repetitive units named short tandem repeats (STRs) and are different to SNP data. The STRs were specifically chosen because they were believed to reveal no known function or trait of a person, but could be compared to crime scene data using the same markers – they were often termed “junk DNA”. However, last year Stanford University biologists thought that with the right combination of databases it may be possible to infer a wealth of information based on a very small set of markers (5 and 6). They also noted that legal assumptions about genetic privacy may not be quite correct, and highlighted the privacy risks that can arise from the cross-linking of databases even from a small number of markers.
Familial DNA testing
It has been held that convicts and arrestees have a lower expectation of privacy than ordinary citizens and that the State has interest in identifying criminals and preventing recidivism -that is why their DNA is on a database. When there is not a direct ‘match’ with a crime scene profile to a person on a police DNA database, then that database may be searched for ‘partial matches’ (when jurisdictions allow it). The scientific rationale is that relatives will share more DNA data, and so family members of a person on a police STR database may be possible contributors to the crime scene DNA with a partial match. This familial DNA testing thus expands a database with ‘virtual’ inclusion of relatives of arrestees, thus expanding “junk” DNA into valuable genealogical charts.
A most notorious cold case and miscarriage of justice from Cardiff in Wales in 1988, known as the Valentine’s Day murder of Lynette White, was solved through familial DNA profiling – after the convictions of three men were ruled unsafe. Crucial blood evidence was found during a re-investigation of the original crime scene and searched on a DNA database for a partial match in 2002. Jeffrey Gafoor pleaded guilty and the largest police corruption trial in Britain followed (7). Other spectacular solutions through familial DNA searching such as the Grim Sleeper serial killer in the USA drew attention around the world.
During September 2018 it was announced that familial DNA profiling had been introduced in Australia through the National Criminal Investigation DNA database (NCIDD). When there is no ‘match’ with a convicted offender or person on the DNA database to an uploaded crime scene DNA profile, that person is excluded but not family members if there is a ‘partial match’. Potential biological relatives to the crime scene profile donor will be ranked according to likelihood of a family relationship using complex statistical methods (see www.anzpaa.org.au and www.acic.gov.org).
This writer has advised in cases where the prosecution used partial DNA searches on the police database as the crime scene profile did not match anyone on it. Then Y-STR profiling was performed on the crime scene profile to determine whether there was a match with any of the partial profiles. Y-STRs are inherited paternally and are found on the Y chromosome; close male relatives will have the same Y-STR profile. When there is a match, police then obtain DNA profiles from the male relative and will pursue an investigation into that person if there is a match with the STR profile.
Evolving research and current practice is showing that police DNA databases can be expanded beyond what was conceived and cast a wider net. Assumptions made about genetics that underlie legal arguments regarding privacy may not be completely true. Technical and ethical issues need to be discussed and it will be of interest to see how this plays out in Australia amid the ethics of who owns your DNA.
Jane Moira Taupin has been a forensic scientist for over 30 years and is currently an independent forensic science consultant. She has reported forensic biology evidence for police agencies in Australia and the United Kingdom, including scene attendance and trials. She has performed review and defence work for Australian States, the United Kingdom, the United States and Thailand. Jane has published many articles in peer reviewed forensic journals on biological evidence and three text books, two on DNA evidence. She has also won national and international forensic science awards.
3. Sense about Genetic Ancestry Testing, Sense about Science, available at www.senseabout science.org
4. Zhang, S., 2018, How a tiny website became the police’s go-to genealogy database, June 1, The Atlantic, available at www.theatlantic.com/science
6. Edge, M., Algee-Hewitt, B., Pemberton, T., Li, J., and Rosenberg, N., 2017, Linkage disequilibrium matches forensic genetic records to disjoint genomic marker sets, Proceedings of the National Academy of Sciences, May 15
7. BBC News, Lynette White: The Cardiff murder that sparked a miscarriage of justice, 14 February 2018 available at www.bbc.com.news/world-