Florence was the elder sister of spree killer Robert Garrow. The film is based on the life of spree killer Charles Starkweather. It was influenced by the crimes of convicted teenage spree killer Charles Starkweather. The name Starkweather is taken from Charles Starkweather, a late-1950s spree killer. Australian spree killer Martin Bryant was also born at the hospital in May 1967. He was murdered on May 4, 1997, by the spree killer Andrew Cunanan. Nicholas Troy Sheley (born July 31, 1979) is an American spree killer. Brett Matthew Paul Thomas (born January 5, 1959) is an American spree killer.