This ped can be found on Portland Island, mostly in areas like Salvatore's House and Trenton. He wears a fedora, a long trench coat, and boots. He is called the Serial Killer, because he looks very much like a similar ped in GTA San Andreas, who is also rumored to be a serial killer.
Players have reported, that the serial killer ped would attack them unprovoked and with no warning at all. Some players reported that the ped spawns with weapons as well. After investigating the weapons part of the myth, he does not spawn with guns, unless the player activates a cheat. The serial killer ped has been investigated thoroughly, and nothing out of the ordinary was discovered about him. The pedestrian exists, but it is proven that he is, in fact, not a serial killer and is just a normal pedestrian.
The pedestrian model was also reused for Marty Chonks, an actual serial killer in Liberty City.