The U.S. Secret Service has released some details about its investigation into comedian John Mulaney over jokes he made about Donald Trump on "Saturday Night Live" last year. 

Mulaney first revealed that he was investigated by the Secret Service during an appearance on "Jimmy Kimmel Live."

"In February, I did a joke that was not about Donald Trump," the comedian explained at the time. "The joke was about how it was a leap year and the leap year was started by Julius Cesar to correct the calendar, and another thing that happened with Cesar was that he was stabbed to death by a bunch of senators because he went crazy. And I said that’s an interesting thing that can happen." 

The file obtained by the AP through Freedom of Information Act request showed that Mulaney wasn't joking when he said he was the subject of an investigation. The bureau contacted NBC but did not interview the comedian for its inquiry, which found no wrongdoing.

The joke was said during Mulaney’s opening monologue during the "Saturday Night Live" broadcast on Feb. 29, 2020.

"Another thing that happened under Julius Caesar, he was such a powerful maniac that all the senators grabbed knives, and they stabbed him to death. That would be an interesting thing if we brought that back now," Mulaney said to laughter from the audience during his monologue.

JOHN MULANEY SAYS HE WAS INVESTIGATED BY THE SECRET SERVICE OVER JOKE 'THAT WAS NOT ABOUT DONALD TRUMP'

John Mulaney performed a joke on 'Saturday Night Live' that got him investigated by the Secret Service. (Kyle Dubiel/NBC/NBCU Photo Bank via Getty Images)

The Secret Service noted other remarks during the monologue, including: "I asked my lawyer if I could make that joke, he said, let me call another lawyer, and that lawyer said yes. I don’t dwell on politics, but I dislike the Founding Fathers immensely. ... I hate when people are like, God has never created such a great group of men than the Founding Fathers. Yeah, the ’92 Bulls. ... That’s a perfect metaphor for the United States. When I was a boy, the United States was like Michael Jordan in 1992. Now the United States it like Michael Jordan now."

Two days after Mulaney’s "SNL" monologue, law enforcement officials contacted Thomas McCarthy, the global chief security officer and senior vice president at NBC Universal, to express the agency’s desire to discuss the joke with the comedian's attorneys.

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The Secret Service file included a report from Breitbart entitled, "SNL: John Mulaney Jokes that Senators Should Stab Trump Like Julius Caesar." The investigation into Mulaney was opened in March and closed in December, five days after the comedian talked about the situation on Kimmel's show.

The Secret Service file notes that Mulaney made no direct threats towards Trump.

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"The person vetting me was very understanding that the joke had nothing to do with Donald Trump because it was an elliptical reference to him," Mulaney said to Kimmel. "I didn’t say anything about him. In terms of risk assessment, no one who’s ever looked at me thought I registered above a one."

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He added: "I said I have been making jokes about him since 2007, so I have been making fun of him for 13 years," Mulaney said. "They said if it’s a joke, then I am cleared by the Secret Service."

The Associated Press contributed to this report.