It's a pretty sure bet it was Otis Toole. The Jeffrey Dahmer link has proven to be a false one.
Toole was the prime suspect for a long time, then was cleared, then named the most likely suspect. John Walsh declared unequivocally for years that Otis Toole was the killer, and after perusing all known evidence the Hollywood police finally posthumously named Toole as the definite killer.
What surfaced afterwards was that there was a lot of bureaucratic red tape in the initial investigation, as well as some shoddy police work that kept Toole from being charged officially, but every investigator that worked the case said that Toole was the only suspect they ever seriously considered.