Hillary Clinton has been questioned by the FBI over her use of emails while she was secretary of state, her campaign says.
A spokesperson for the Democratic presidential candidate said it was a voluntary interview.
Hillary Clinton denies handling classified information in her private emails.
The former secretary of state said she set up the email address for reasons of convenience.
However, a state department inquiry accused Hillary Clinton and other former US secretaries of state of poorly managing email security.
The Justice Department is now seeking to establish whether this constitutes a criminal offence.
On July 1, the US Attorney General Loretta Lynch said she would accept the findings of the FBI and prosecutors, when deciding whether to charge Hillary Clinton.
On June 30, it was revealed that Loretta Lynch had met former President Bill Clinton in what she described as a “social” meeting but which she admitted would “cast a shadow” over the way her role in the case would be perceived.