ORDINARILY, the sex-offender who attacked a woman in Birmingham, UK, would never have been caught. But thanks to a novel twist on DNA profiling a man is now awaiting sentence for the crime.
DNA profiling has become such a successful forensic tool it is easy to forget it has serious limitations. One kind of DNA sample that has until now defied useful analysis is a mixed one, containing genetic material from more than one person. If two people have been smoking the same cigarette, for example, or drinking from the same glass, any attempt to produce a DNA profile yields…
