The esteemed documentarian looks back at the shocking murders with a new lens, questioning how much anyone really knows about why it happened

“I’m quite convinced that, no matter what I say, I’m not going to be able to convince you to kill for me,” film-maker Errol Morris says drily. “And, alas, I have to say that I don’t have the desire to kill anybody or to convince you to kill on my behalf. It just isn’t there. Call it a weakness of will or weakness of character.”

This is not a sentiment that an interviewer is used to hearing from an interviewee. But it makes more sense in context. Morris, who has previously worked as a private detective, is discussing his new documentary, streaming on Netflix from Friday, which challenges official accounts of the most infamous killing spree of the 1960s.