"Based on our review, we have not changed our conclusions that we expressed in July," Comey wrote in the new letter to congressional committee chairmen.
Comey dropped a bombshell on the presidential race last month when he sent a letter to Congress saying the FBI had discovered emails in a separate investigation that could be connected to the now-closed probe of whether Clinton mishandled classified information. The move infuriated Democrats and emboldened Republican nominee Donald Trump.
It's impossible to know before results are tallied what impact Comey's actions first raising a vaguely worded red flag 11 days out, and then lowering it two days from the election will have on the contest. But the news could help Clinton put to rest a controversy that has dogged her in the 2016 race's closing days, helping Trump narrow a polling gap nationally and in key battleground states.
Trump assailed the FBI's handling of the matter, though he did not directly address Comey's announcement at a rally in Sterling Heights, Michigan.
"You can't review 650,000 new emails in eight days. You can't do it, folks," Trump said, adding, "Hillary Clinton is guilty. She knows it, the FBI knows it, the people know it, and now it's up to the American people to deliver justice at the ballot box on November 8."
"Today's letter makes Director Comey's actions nine days ago even more troubling," Feinstein said in a statement. "There's no doubt that it created a false impression about the nature of the agency's inquiry."
She added: "The Justice Department needs to take a look at its procedures to prevent similar actions that could influence future elections."
"We went through this as fast as we could," a senior law enforcement official told CNN, with another law enforcement official saying investigators worked "around the clock" to review the large volume of emails.
The FBI found the new emails as part of its separate investigation into a sexting incident by Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin.
The thousands of new emails were mostly personal and duplicates of what had already been seen, law enforcement officials said in explaining how the conclusion was reached so quickly. The laptop which was found was about a decade old with lots of personal content on it not relevant to the investigation, according to one source.
The probe is considered over with regard to Clinton. Though with not all the deleted emails recovered and not all the devices in FBI's possession, it is always possible something else could turn up that would require more review.
There were some classified emails found, but law enforcement officials stressed the issue is not the classified information so much as proving intent. The sources would not specify if the the classified messages were new or duplicates of ones already reviewed, nor would would officials say how many there were and what levels at which they were classified.
"Keep in mind we are focused on intent," the official said. "We know there are classified materials, but that doesn't change the conclusion reached back in July."
As for others who were part of the probe, including Abedin, the FBI is still working on some remaining aspects of the review, including determining how the emails ended up on the laptop in the first place. Abedin's attorneys have said she doesn't know why these emails were there because this wasn't a computer she used.
It isn't uncommon to come across new evidence after concluding a probe which is what happened here in October.
Normally, investigators take a look to see if anything changes in their conclusions and it's not a controversial issue. This case isn't a normal case, given the election and the stakes.
