Sometimes, finding a title is the hardest thing about making a film. For Matt Tyrnauer, on this occasion, it was the easiest. “Never before has a sitting president delivered a film title for me,” he told me. During the first month of Robert Mueller’s investigation into Donald Trump’s alleged corruption, in a moment of frustration with the legal and public-relations walls that seemed to be closing in on him, the president blurted something out to his White House advisers: “Where’s my Roy Cohn?!”

Watching Tyrnauer’s new documentary about Cohn, which premieres in competition at Sundance today, it’s easy to pinpoint what a young Donald Trump was yearning for back in January 2018: a ruthlessness that somehow came off as charming, a toughness punctuated with a wink at supporters and a jab at detractors, a commitment to getting one’s way no matter what. And what did Roy Cohn, the notoriously malicious lawyer most infamous for helping Senator Joseph McCarthy carry out the Red Scare, see in Trump?

“I think he saw an up-and-comer, a tall, blond, handsome rich kid, to whom he was always attracted as a short and unattractive, albeit brilliant, frustrated person,” explained Tyrnauer. “And he had a long track record of befriending the handsome scions of certain privileged families in the world that he inhabited.”

For Tyrnauer, a Vanity Fair contributing editor whose previous documentaries include Valentino: The Last Emperor, Studio 54, and Scotty and the Secret History of Hollywood, Where’s My Roy Cohn? was born in two parts.

During the lead-up to the 2016 presidential election, as Tyrnauer was reviewing hundreds of hours of archival footage for Studio 54 (which premiered at Sundance last year), he found himself face-to-face with Cohn, who had defended Studio 54’s co-founders, Ian Schrager and Steve Rubell, after the raid on their nightclub in December 1978. “It’s some of the greatest archival footage I've ever seen,” Tyrnauer said. “It’s Roy Cohn, [the] pit bull, mob lawyer, just having impromptu press conferences with every news camera in Radio City trained on him, barking at the press, and doing this performance as the lawyer of lawyers.”

Tyrnauer had known the basics of Cohn’s story: that he had been Senator McCarthy’s right hand in the post-World War II anti-communist Red Scare and the lesser known Lavender Scare, which targeted gays working in the government. He knew that Cohn had actively campaigned to have Ethel and Julius Rosenberg sentenced to death by electric chair based on their conspiracy to commit espionage. Tyrnauer had also seen Angels in America, the Tony Kushner play that includes Cohn as a character and incorporates aspects of his death from AIDS, his denial of his own homosexuality, and his overall moral turpitude.