GENETIC analysis has been used to prove a jilted lover deliberately infected his girlfriend with HIV.
Richard Schmidt, a former gastroenterologist in Lafayette, Louisiana, is now serving a 50-year sentence for the attempted murder of nurse Janice Trahan. When Trahan broke off their 10-year affair, Schmidt injected Trahan with a cocktail of blood from two of his patients, an HIV-positive man and a woman with hepatitis C, on the pretext of giving her a vitamin injection. The genetic evidence established that the HIV strain that Trahan has almost certainly came from Schmidt鈥檚 patient.
Although the crime was committed in 1994 and Schmidt was convicted in 1998, the full scientific details could only be published last month, after the US Supreme Court rejected an appeal earlier this year. A similar forensic technique has already been used in a rape case in Sweden, but it is the first time such evidence has been used in US courts.
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HIV mutates very quickly, so it is possible to create a 鈥渇amily tree鈥� showing how different viruses are related by comparing their DNA sequences. A team led by Michael Metzker at the Baylor College of Medicine in Houston analysed 50 viral particles from the patient and another 50 from Trahan. The researchers compared the sequence of two HIV genes with the same genes in samples from 32 local HIV patients and published sequences.
All 50 viral particles from Trahan were slightly different from each other. But as expected, their similarities made them cluster on the family tree. And this cluster matched that of the viruses from Schmidt鈥檚 patient (Proceedings of the National Academy of Sciences, vol 99, p 14292). So Metzker could tell the court that it was very unlikely Trahan caught the virus from anyone else. 鈥淭he science was just another piece of evidence that put the puzzle together,鈥� he adds.