The FBI interviewed Hillary Clinton on Saturday morning as part of the investigation into her use of a private email server for official emails while she served as secretary of State, campaign spokesman Nick Merrill said.
"She is pleased to have had the opportunity to assist the Department of Justice in bringing this review to a conclusion,'' Merrill said in a statement, describing the meeting as voluntary. "Out of respect for the investigative process, she will not comment further on her interview.''
The 3½-hour interview was conducted at FBI headquarters in downtown Washington, according to a Clinton aide. The meeting had been anticipated as the FBI investigates whether classified information was compromised by her email arrangement.
Republican National Committee Chairman Reince Priebus described the questioning of Clinton as unprecedented for a major party presidential candidate.
"That the FBI wanted her for questioning reinforces her central role in deliberately creating a culture which put her own political ambitions above State Department rules and jeopardized our national security,'' Priebus said.
The Justice Department aim is to finish its probe and recommend whether charges should be filed before the Republican and Democratic national conventions, which start the week of July 18, ABC News reported.
On Friday, Attorney General Loretta Lynch said she will accept the decision of career prosecutors, investigators and FBI Director James Comey on whether to bring criminal charges in the investigation.
The unusual public announcement during an event in Aspen, Colo., came as the attorney general faced a storm of criticism related to an awkward encounter with former president Bill Clinton after the two crossed paths earlier this week at Phoenix's Sky Harbor International Airport.
"This case will be resolved by the team that has been working on it from the beginning,'' Lynch said, acknowledging that the meeting with Bill Clinton "cast a shadow'' over the ongoing inquiry.
If the FBI director and the Justice Department prosecutors disagree on whether to prosecute, Lynch may have to delegate that tie-breaking decision to a deputy, said professor Carl Tobias of the University of Richmond School of Law.
The State Department's Office of Inspector General issued an audit in May that found the former secretary of State disregarded cybersecurity guidelines by using a private email server during her tenure there and she did not seek authorization for her email account.
The audit also found Clinton and her predecessors as secretary of State poorly managed computer systems. By the time Clinton took over as secretary of State in 2009, the standards for email security were "considerably more detailed and more sophisticated" than for previous secretaries of State. The department revised guidelines through 2011, according to the report, and "Secretary Clinton's cybersecurity practices accordingly must be evaluated in light of these more comprehensive directives."
Nevertheless, the recommendations in the report were limited to forward-looking measures to better inform employees of department policies and for improving cvbersecurity.