An examination of the Crystal Faye Todd case. In 1991, the 17-year-old was brutally murdered in Horry County, South Carolina. The police asked 52 male acquaintances to provide blood samples so that they could compare the DNA to semen found at the murder scene. The process eliminated all but one young man---and he's now serving a life sentence.

An examination of the first time animal DNA was used to solve a criminal case. In 1994 Canada, on Prince Edward Island, the body of Douglas Beamish's estranged wife was discovered. Authorities linked 20 cat hairs found on her jacket to a cat owned by Beamish's parents, with whom he lived. Scientists estimated that chances that the hairs came from another feline were one in 50 million. A jury later convicted Beamish of second-degree murder; he was sentenced to 18 years without parole.

An outbreak of food poisoning in 1984 Oregon leads authorities to a religious cult.

A woman's death is investigated. The husband claims it was suicide; but the police suspect otherwise.