Prosecutors like Mueller generally cringe when a witness speaks at length in public before a case has wrapped up. Comey’s blockbuster book and accompanying media tour, which kicks off in primetime on Sunday, will also expose him to the watchful eye of Trump allies and defense lawyers ready to exploit any inconsistencies in his accounts to their clients’ benefit.

“I’d have a conniption if I knew one of my witnesses was going to be writing a book,” said Nick Akerman, a former assistant U.S. attorney and Watergate prosecutor.

“From a prosecutor standpoint, you want a witness who hasn’t gone out and made lots of statements that can be used to cross examine him,” Akerman added. “What he puts in there, he’s got to realize that’s his story and that’s what he’s sticking by.”