Holmes apparently took the killers to the house and watched it happen. He was pissed off at the people who lived there because one of the dealers had been robbed a few days before and Holmes had got the blame, they tied him to a chair and beat the shit out of him, so when these other guys wanted to rob the place, Holmes took them to the house.
After he died his wife at the time said he got home the morning after the killings really early and his shirt was covered in blood.
Fucking LA degenerates. That house in Laurel Canyon was a notorious dope hangout, apparently the neighbors heard shouting and screaming at about 3am but thought nothing of it because weird shit was always happening there.
Some workmen that were down the street the next day heard the only survivor moaning, she'd been laid there 12 hours when they found her.
All the other people were dead but she survived, but they had to remove a chunk of her skull and she lost 3 fingers, the damage to her brain meant she had total amnesia around the event (unless she was afraid to talk) John Holmes was quickly tied to it and the cops tried to pin it on him but he got off, he only served 110 days or so for contempt because he flat refused to cooperate with the LAPD at all.