Former FBI Director James Comey has spoken to House investigators behind closed doors for almost seven hours, begrudgingly answering questions about the Justice Department's decisions during the 2016 presidential election.
Comey, who appeared on Friday under subpoena, announced after the meeting that he would return for more questioning December 17.
Appearing annoyed, he said "we're talking about Hillary Clinton's emails, for heaven's sake, so I'm not sure we needed to do this at all".
A transcript of the interview, expected to be released shortly, "will bore you," Comey said.
Two GOP-led committees brought Comey in as they sought to wrap up a yearlong investigation into the department's decisions in 2016.
Republicans argue that department officials were biased against Donald Trump as they started an investigation into his campaign's ties to Russia and cleared Democrat Hillary Clinton in the probe into her email use. Comey was in charge of both investigations.
Democrats have said the investigations by the House Judiciary and Oversight and Government Reform committees are merely a way to distract from and undermine special counsel Robert Mueller's Russia probe.
Mueller took over the department's investigation when he was appointed in May 2017.
After the questioning was underway, some Republicans signalled they were unhappy with Comey's level of cooperation.
California Representative Darrell Issa said Comey had two lawyers in the room, his personal lawyer and a lawyer from the Justice Department.
He said the department lawyer repeatedly instructed Comey not to answer "a great many questions that are clearly items at the core of our investigation".
Democrats disagreed that Comey wasn't cooperative.
"He answered the questions he had to answer," said Representative Raja Krishnamoorthi of Illinois. But he added that he was left with the impression that "we got nowhere today".
Florida Representative Ted Deutsch said the Republican majority "wishes to only ask questions still about Hillary Clinton's emails, all to distract from the big news today, which is what's happening in court".
As the interview with Comey ended, Mueller revealed new details about his Russia investigation in court on Friday in the cases of Trump's former campaign chairman, Paul Manafort, and former personal lawyer Michael Cohen.
It was unclear if Comey is returning the week after next because Republicans felt he was being uncooperative, or if it was an issue with timing.
While such closed-door interviews often extend late into the night, lawmakers said on Friday that the interview would end in the afternoon because of scheduling issues.
Just as the meeting ended, President Trump tweeted that "it is being reported that Leakin' James Comey was told by Department of Justice attorneys not to answer the most important questions. Total bias and corruption at the highest levels of previous Administration. Force him to answer the questions under oath!"
While it was uncertain if Comey spoke under oath on Friday, lying to Congress is a crime under any circumstance.