Starkweather (2004)

Since childhood, Nebraska farm-boy Charles Starkweather has a schizophrenic Mr. Hyde side, a nameless dark figure, who inspires him to be cruel for the kicks. Having grown up to a 19 year old garbageman and fallen in love with weird girl 14 year old girlfriend Caril Ann Fugate, he gets completely out of control, killing of her entire family and various other singles of groups during their ensuing inter-state car-chase, hunted down by sheriff Merle Karnopp and a growing army of cops and press, then unprecedented.