Corroboration, corroboration, corroboration.
But Comey — whose nearly three hour testimony included statements that Russia interfered with the 2016 election and that Trump asked him to drop the Michael Flynn investigation — didn't leak those documents on his own. He asked friend and Columbia law professor Daniel C. Richman to do it in hopes that it would lead to the appointment of a special prosecutor for the Russia investigation, CNN reports.
Both in a written statement and during the testimony, Comey stressed that his "gut feeling" told him to document his unusually frequent interactions with the president.
“I was alone with the president of the United States. I was talking about matters that touch on the FBI’s core responsibility and that related to the president-elect personally," Comey said. "Then [there was] the nature of the person. I was honestly concerned he might lie about the nature of our meeting, so I thought it really important to document."
That statement followed others he made that accused the president of defamation and smearing. Comey also said he believes he was fired for his handling of the Russian collusion probe.
In testifying about the leak, Comey referenced a May 12 tweet from the president that prompted him to ensure a corroboration.
"The President tweeted on Friday, after I got fired, that I better hope there's not tapes," Comey said. "I woke up in the middle of the night on Monday night, because it didn't dawn on me originally, that there might be corroboration for our conversation, there might be a tape. And my judgment was I needed to get that out into the public square. So I asked a friend of mine to share the content of the memo with a reporter."
Comey was fired three days prior to Trump's veiled threat.
According to NBC News, Comey and Richman's friendship spans 30 years. Richman, a formal federal prosecutor with the U.S. Attorney's Office for the Southern District of New York, vocally supported his friend after it was announced prior to November's election that he would be looking into Hillary Clinton's emails.
"When you have an obligation to disclose or to qualify, you do it full-stop," Richman said last year, according to NBC. "You don't worry about timing, you don't worry about how it will be read or spun by others."