Twenty years ago, Keith Davison raped a 24-year-old waitress on the Isle of Wight in the UK. He thought he had got away with it, but a DNA sample taken from Davison's daughter led to his conviction. The DNA sample was taken from his daughter as a result of a minor assault. This technique known as "familial searching" links DNA from a crime scene with the DNA of a relative of the perpetrator. Davison was sentenced to eight years in jail at Portsmouth Crown Court and will be put on the sex offenders register for life. 