Manson was in that crowd more than they will admit. Polanski had been lovers with Bobby Beusoliel before Bobby joined up with Manson's Family. They were both part of LaVey's Church of Satan before he did. So was Susam Atkins. Bobby was in one of Polanski's movies. Susan used to be a dancer or topless waitress at some bar before she joined CoS. Manson was running a sex ring of underage girls and he was being handled by a DS agent who worked with his parole officer, both had the same last name. Manson was breaking parole violations and the parole officer knew all about it but let it go on. Manson was trained in cult mind-control.  See David McGowan's Laurel Canyon series.