It has stopped destroying untested kits after five years, but other police departments continue the practice. Many police departments still use DNA evidence as they have used fingerprints and tire tracks, to rule a suspect in or out. But the new DNA databanks make the evidence useful for matching cases to convicted offenders, or to other cases in which a suspect may be known. About one-third of the agencies test less often. And about one-quarter weren't sure.
Cities vary widely in their use of DNA testing.
In Los Angeles, the police department buys a new, 40-foot refrigerated trailer truck every six months, just to hold DNA evidence. When you got a court date, when you go to trial, then it will happen. The three DNA samples that identified a serial rapist in Milwaukee were collected in 1993. In each case, on the city's north side, a man grabbed a woman from behind, told her that he had a knife, took her to a quiet place, raped her, and demanded money, police said. After she reported the crime, vaginal and cervical swabs of semen were collected at a hospital.