Federal investigators have questioned an independent reporter who claimed credit for posting a message online that officials initially believed to be a credible threat from a hacking group.

On Wednesday, Tennessee-based writer David Garrett came forward as the person responsible for a December 20 message posted on the website PasteBin that purported to come from hackers identifying themselves as the “Guardians of Peace” or GOP.

In the post, a person claiming to be associated with GOP mocks the cable news channel CNN for a report in which they sourced messages posted on the website PasteBin that were associated with the hacking collective. The message included a link to a YouTube video called “You are an idiot” as well as a demand that CNN had one day to “give us the Wolf,” an apparent nod to news personality Wolf Blitzer.

The message was similar in tone to one posted earlier in the day directed at the FBI. On Wednesday, The Intercept’s Jana Winter published an internal FBI memorandum in which federal investigators warned of threatening messages posted on PasteBin that seemed to indicate forthcoming attacks by the GOP. The memorandum mentioned the message directed to the FBI and a second message made to a “news media organization,” which The Desk identified as CNN.

Shortly after the reports, Garrett came forward as the author of the message to CNN. In a series of tweets with The Desk, he claimed the post was made as a joke intended to highlight what he considered to be a shortcoming in CNN’s use of PasteBin as a legitimate news source.

“It wasn’t a threat,” Garrett said. “It was a joke.”

Federal investigators were not amused: On Thursday, FBI agents questioned Garrett over the post and his subsequent admission online.

“They seemed most interested in the reporters I’ve talked to or have contacted me,” Garrett told The Desk in a follow-up interview. “They were also interested in my level of expertise and it’s my impression, based on their questions, that they believe I’m a hacker.”

Garrett said FBI agents didn’t contact him before the interview, though he claimed investigators had already connected his computer’s IP address to the post made on PasteBin.

“I didn’t hide my [IP address] because I had no ill intent,” Garrett said. “They knew who I was right away when I posted it so I am a little surprised that if this was such a big deal that they didn’t contact me.”

In its intelligence bulletin, the FBI offered no explanation as to how it authenticated the PasteBin message to CNN. Before Wednesday, the agency also gave no official indication it was investigating a U.S. citizen in connection with the online posts.

Garrett said he was not read his Miranda rights and had no lawyer present during the interrogation. A reporter with the Knoxville News-Sentinel accompanied him to the FBI field office but was told by agents she could not be present during the questioning, he said.