FBI Director James Comey said Sunday that the agency has reviewed all of the Hillary Clinton emails recently discovered in an unrelated case and that his conclusion in July not to prosecute Clinton after the FBI’s original investigation into her use of a private email server still stands.

Comey informed Congress on Oct. 28 that the agency would in the unrelated case review additional emails related to Clinton’s time running the State Department from 2009 to 2013.

“Since my letter, the FBI investigative team has been working around the clock to process and review a large volume of emails,” Comey said Sunday in a follow-up letter to Congress. “During that time we reviewed all of the communications that were to or from Hillary Clinton as secretary of state. Based on our review, we have not changed our conclusion.”

A Department of Justice spokesperson said that agency and the FBI “dedicated all necessary resources to conduct this review expeditiously.”

When asked where the email investigation stands after Comey's letter, a senior law enforcement official close to the probe described the matter to Fox News as "closed."

Attorney General Loretta Lynch was briefed on the FBI's findings before Comey sent the letter, the official said. Lynch's position on the email investigation, "has not changed," meaning that she'll accept the findings of the agents and prosecutors on the case, according to the official.

In addition, Fox News is told that Lynch maintains her confidence in Comey and his ability to run the FBI.

The letter was another unexpected turn in the close White House race between Clinton and Republican rival Donald Trump, with Election Day on Tuesday. Whether the close of the new probe takes away Trump apparent late momentum remains unclear.

Reaction from the campaign trail and on Capitol Hill to the letter, which still appears to leaves some unanswered questions, was swift and largely partisan.

“We're glad this issue is resolved but for the record, this could easily have been learned before 1st letter was sent,” tweeted Brian Fallon, a spokesman for the Clinton Democratic presidential campaign.

The new case is purportedly related to ex-New York Democratic Rep. Anthony Weiner using a laptop he shared with estranged wife and top Clinton aide Huma Abedin for “sexting” an apparently underage female.

Comey’s letter last month said only that a new batch of emails “appeared to be pertinent” to the FBI’s original Clinton email investigation.

Comey in July concluded the FBI investigation into Clinton’s use of the private server system while at the State Department by saying some of the emails contained classified information and that Clinton has been “extremely careless.”However, he declined to recommend criminal charges to the Justice Department, and the case was effectively closed.

Clinton has not yet commented yet on the letter, but at a rally in Sterling Heights, Michigan, Trump told supporters that the investigation "will go on," and Clinton was being "protected by a rigged system."

"You can't review 650,000 emails in 8 days," Trump said. "Now it's up to the American people to deliver justice at the ballot box on November 8."

Ealier in the day, Trump running-mate Mike Pence said at a rally in North Carolina: “The FBI last summer concluded that Hillary Clinton having classified documents on that private server was extremely careless. And I guess today, I don’t know if you heard, today they announced that they had not changed that conclusion. But you know, mishandling classified information is a crime.”

The Clinton campaign and it supporters howled that Comey with his October letter had injected himself in the closing days of the very close White House race, while providing little information about the emails and the new probe.

Utah GOP Rep. Jason Chaffetz, chairman of the House Committee on Oversight and Government Reform, told Fox News’ “Special Report with Bret Bair” on Sunday night said he wasn’t surprise by the letter and continues to have questions -- including whether Clinton has lied under oath about mishandling classified information in her State Department emails and what is the threshold to prove criminal intent.

“What level do you need to get to to actually prove intent?” Chaffetz asked. “They did not answer the question yet as to whether Hillary Clinton has committed perjury.”

House Speaker Paul Ryan, the top Republican in Congress, said Sunday night: "Regardless of this decision, the undisputed finding of the FBI's investigation is that Secretary Clinton put our nation's secrets at risk and in doing so compromised our national security.”

“She simply believes she's above the law and always plays by her own rules. ... The American people should not have to endure four more years of their scandal and baggage. … Let's bring the Clinton era to an end by voting for Donald Trump on Tuesday."

Trump landed in Minnesota for a rally after Comey's announcement was made public.

He made no direct mention of the issue and continued to insist that Clinton would be under investigation during her potential presidency.

"She's protected by a rigged system," he told supporters. "She shouldn't even be allowed to run for president."

House Minority Leader Nancy Pelosi, D-Calif., said after the letter’s release: "While the original letter allowed days of innuendo and falsehood by Republicans desperate to divert attention from themselves, the FBI's swift and thorough review should finally close the door on this Republican sideshow.”

Fox News' Matt Dean and The Associated Press contributed to this report.