Former FBI director James Comey hinted several times during Thursday's testimony that special counsel Robert Mueller might already be exploring an obstruction of justice charge against Donald Trump. Though Comey repeatedly declined to give his personal estimate of whether Trump had committed obstruction, he dropped bread crumbs like this:
That’s a conclusion I’m sure the special counsel will work toward, to try and understand what the intention was there and whether that’s an offense.”
Comey also steered away from publicly talking about certain information related to Attorney General Jeff Sessions, saying that he and his FBI colleagues were "aware of facts" about Sessions' engagement with the Russia investigation that he couldn't "discuss in an open setting."
That information could be classified, but it also might be material to an obstruction of justice charge related to Comey's firing. (As a Daily Kos reader pointed out Thursday, former Nixon Attorney General John Mitchell was ultimately found guilty of both perjury and obstruction of justice related to the Watergate scandal.)
Another thing Comey declined to speculate on in “an open setting”: whether Donald Trump colluded with Russia.
Remember, Mueller cleared Comey to testify—meaning they discussed what was "off limits" at a public hearing beyond the normal constraints of not revealing classified information. So Comey has at least some sense of the direction Mueller is headed based on that conversation, regardless of whether anything was explicitly stated between the two.
Comey also indicated during testimony that he had already turned over his memos documenting his interactions with Trump to special counsel Mueller.
Comey had two goals during Thursday's hearing—one was to get his side of the story out about his interactions with Trump. The other was to avoid treading on any investigations currently under way.
In that sense, what he was unwilling to say was equally as telling as what he did say.