Columbine. Oklahoma City. The Brink’s cop-killing robbery. Gabby Giffords. The 2005 London transport bombings. These and many other rampages had something in common: All of the attackers had copies of “The Anarchist Cookbook,” a step-by-step manual for revolution.

So how does the author of the notorious 1971 book, with its detailed instructions for making TNT, booby traps and napalm feel about the book? “This is the first time I’m becoming aware of the laundry list of associations that the book has had,” writer William Powell tells filmmaker Charlie Siskel in an unnerving new documentary, “American Anarchist.”

The director (a nephew of the late film critic Gene Siskel) tracked the aging Powell down in France to confront him with a relentless, prosecutorial case, damning him with his own words, “Allow the fear and loneliness and hatred to build up inside you,” Powell urged readers in the book. “Allow your love of freedom to overcome the false values place on human life … respect must be earned by the spilling of blood.”

“I remember thinking, ‘That is a cool turn of phrase,’” Powell tells Siskel in this study on the banality of evil.

An upper-class kid from Long Island, Powell, the son of a spokesman for the UN, was kicked out of boarding school for “Gently pushing a teacher’s car into— a ravine would be an exaggeration.”

Living on East 10th Street near Avenue A at the peak of antiwar protests, he holed up in libraries poring over army field manuals, transcribing the secrets for explosives and weapons. “The time is for a mass uprising armed with single-minded, deadly intolerance,” he wrote, finding a radical publisher who (unnoticed by Powell) assigned himself sole possession of the copyright. When Powell finally disavowed the book in a 2013 piece for The Guardian, he was unable to take it out of circulation. (A heavily edited version is still sold on Amazon.com.)

Powell, who at one point says he feels “remorse” but not “regret,” spent decades in denial while teaching special-needs kids. Only during the making of this riveting film does he seem to confront, albeit with bland disinterest, the horror of what he has done. “It’s not, ‘Oh, let’s go and burn the government down.’ That’s not there,” Powell insists, until Siskel has him read monstrous passages from the book advocating exactly that.

Watching Powell try to find some middle ground between defending the indefensible and begging humanity’s pardon makes for a chilling experience. “I think,” he says weakly, “I was advocating for people to think for themselves.” Shortly after the film was completed, he died.