Using phylogenetics, scientists have been able to inform prosecutors about how closely related viral or bacterial strains are, information that can help support criminal cases, Nature reports.
"What we are doing is a virus genealogy," the University of Oxford's Oliver Pybus tells Nature.
For instance, Spanish scientists were able to trace a cluster of hepatitis C cases to an anaesthetist, Juan Maeso, who apparently had been injecting himself with some of his patients' morphine and then using the same needle to inject the patients with the rest of the drug. As the University of Valencia's Fernando González-Candelas and his colleagues reported in BMC Biology last summer, they sequenced the NS5B and E1-E2 regions of the viral genome from 322 HCV-1a-infected patients and 44 local controls, which they then compared to sample from Maeso. Of those, 275 patients appeared to have viruses highly similar to Maeso's. The researchers were also able to estimate when patients were infected. Maeso was found guilty and sentenced to nearly 2,000 years in jail, Nature notes.
Additionally, a similar approach linked the anthrax strains used in the 2001 bioterror attacks to a variant of the lab-based Ames strain and then to Bruce Ivins at the US Army Medical Research Institute of Infectious Diseases, though a 2011 National Academy of Sciences review found that the strength of genetic analysis in that case was "overstated." Nature notes, in that case, the importance of the phylogenetic data was not tested as it did not go to trial; Ivins committed suicide in 2008.
The use of such approaches in criminal cases makes some people wary. "You can never prove guilt," Anne-Mieke Vandamme from the University of Leuven in Belgium tells Nature. She and a number of colleagues are working to establish guidelines for both the technical aspect of the work as well as for how to present such information to courts.
"It's still an emerging field," adds Bruce Budowle, who worked on the anthrax case with the FBI. "We expect that what we are using today, we probably won't be using two years from now."