Paul Krassner alleged that the LAPD told him there were some swinger parties of Manson girls with Hollywood celebs like Sammy Davis Jr (who joined the Church of Satan and he is on record explicitly stating his goal of getting to go to sex parties) and that recordings were made of these affairs.
Yes, Krassner has written about that, and other authors have provided more specifics. Davis talked about that himself, although one of his friends says he concealed the extent of his involvement with the Church of Satan—that it went deeper than he acknowledged. Davis specifically mentioned seeing Jay Sebring at a Satanic orgy. Davis, Peter Lawford, and Frank Sinatra were invested in an LA club that was frequently used for such activity—Lawford being JFK and RFK’s pimp when they were in LA. . .Getting back to Fonda, the week of Tate-LaBianca, there was a party held at Cass Elliot’s house (near the Polanski residence) in honor of her husband Roger Vadim, where the guests sexually assaulted a drug dealer who was a friend of Manson’s, as punishment for the dealer burning Jay Sebring on a $2,000 cocaine deal. Sebring apparently filmed the incident, as he dropped off some undeveloped film at that time.