Almost every email reviewed in the latest FBI probe were duplicates of emails already investigated or personal emails, a source says.
Law enforcement sources say a faction within the FBI's New York field office are known to be hostile to Hillary Clinton.
Questions swirl as the bureau becomes more deeply entwined in the election.
Senator Harry Reid accuses FBI Director James Comey of violating the Hatch Act, which bars the use of a federal government position to influence an election.
Reports say FBI investigators probing Anthony Weiner's communications found the emails weeks ago but waited to tell Comey.
The truth is James Comey didn't have a choice.
After long maintaining that she did not send or receive classified information through her private email server, Clinton acknowledged she may have unwittingly done so.
The announcement came after the Justice Department declined to bring criminal charges.
Paul Ryan, Donald Trump and other Republicans are criticizing the FBI's decision regarding Clinton's use of email as secretary of state.
The FBI director did say there was evidence of extremely careless handling of emails by Hillary Clinton.
"Apple is not a demon. I hope people don't perceive the FBI as a demon."
"It's a bit of a technological corner case, because the world has moved on to 6's," FBI Director James Comey says.
FBI Director James Comey admitted that "a mistake was made" in handling the iPhone of San Bernardino shooter in changing the password on his Apple ID the day after the shooting.
The hearing signals the first move by Congress, which has stayed quiet so far on the iPhone encryption case.
Comey said the FBI had taken terrorism investigations "up a notch" since the Paris attacks.
Former White House National Security Adviser Richard Clarke calls the push "unseemly."