His first known murders were in 1972 when he killed a young boy and a girl in his hometown of Watertown, New York. Under the terms of a plea bargain, Shawcross was allowed to plead guilty to one charge of manslaughter, for which he served 14 years of a 25-year sentence. He killed most of his victims in 1988 and 1989 after being paroled early which led to criticism of the justice system. A food service worker, Shawcross trawled the streets of Rochester in his girlfriend's 1984 sky blue Dodge Omni (later using her blue-grey 1987 Chevy Celebrity), looking for sex workers to kill.