Researchers have built a new approach to find male suspects who intentionally infected women partners with HIV during unprotected sex.

The phylogenetic approach can generate the history of how the viruses evolved in different people. The authors, who said this is the first case study to establish the direction of transmission, would provide “evolutionary forensics” evidence how the virus was transmitted from one individual to another.

"This is the first case study to establish the direction of transmission," Mike Metzker, of Baylor College of Medicine and coauthor of the new study, said. The paper is published in the Proceedings of the National Academy of Sciences.

HIV analysis differs from DNA screening of an indivdual because HIV mutates all the time when it makes new virions.

"Phylogenetic analysis allows us to reconstruct the history of the infection events," David Hillis, of University of Texas, Austin, and a coauthor of the new study, said. “We can identify the source in a cluster of infections because some isolates of HIV from the source will be related to HIV isolates in each of the recipients."