In early 2010, a mod was released for GTA San Andreas that added multiple myths and creatures to the game at the Angel Pine Junkyard. Two of these were the Junkyard Killer, and the Headless Man, who was killed by the Junkyard Killer. The mod also added a little back-story to the existence of the Killer and the Headless Man.
According to the story, the Junkyard Killer killed a college student and sliced his head off. After the Junkyard KIller killed the college student, he was killed by a group of unknown people (probably serial killers) and they dumped his body in the junkyard next to Mount Chiliad.
His flesh was burned and after a few years his body was somehow reanimated. He has a pump action shotgun and he kills anyone who gets close to the junkyard. He is wearing a western hat, boots, and a rain coat. All his clothes are black. Players say that the black color is because of his body being burned. He also wears a white mask.
It's hard to find him as he might be transparent and he might also be seen fighting the Headless Man under Blueberry Bridge.