The FBI has obtained a warrant to search the emails found on a computer used by former Congressman Anthony Weiner that may contain evidence relevant to the investigation into Hillary Clinton’s private email server, according to law enforcement officials.

One official said the total number of emails recovered in the Weiner investigation is close to 650,000 – though that reflects many emails that are not in any way relevant to the Clinton investigation. Officials familiar with the case said, though, the messages include a significant amount of correspondence associated with Clinton and her top aide Huma Abedin, Weiner’s estranged wife.

The agents investigating Clinton’s use of a private email server knew early this month that messages recovered in a separate probe might be germane to their case, but they waited weeks before briefing the FBI director, according to people familiar with the case.

FBI Director James Comey has written that he was informed of the development Thursday, and he sent a letter to legislators the next day letting them know that he thought the team should take “appropriate investigative steps designed to allow investigators to review these emails.”

That missive ignited a political firestorm less than two weeks before the election. Almost instantly, Comey came under intense criticism for his timing and for bucking the Justice Department’s guidance not to tell Congress about the development. And his announcement means that Clinton could have to contend with the news that the FBI has resumed its investigation of her use of a private email server – without any real clarity on if its investigators will actually find anything significant – up to and beyond Election Day.

People familiar with the case said they had known about the messages since soon after New York FBI agents seized a computer related to their investigation into Weiner, who is alleged to have exchanged explicit messages with a 15-year-old girl.

Abedin has told people that she is unsure how her emails could have ended up on a device she viewed as belonging to her husband, according to a person familiar with the investigation and civil litigation over the matter.

An announcement from the FBI in early October, when the emails were discovered, might have been less politically damaging for Clinton than one coming less than two weeks before the Nov. 8 election. It is also unclear what agents have been doing in the intervening time – for instance, whether they were trying to learn more about the emails before notifying Comey. An FBI spokesman declined to provide a statement.

Comey wrote in his letter to Congress, “We don’t know the significance of this newly discovered collection of emails,” and federal law enforcement officials have said that investigators on the Clinton email team still had yet to thoroughly review them. They would need a warrant to do so, and as of late Saturday, they had not yet acquired one, according to an official familiar with the case.

Why authorities had not yet obtained a warrant also is unclear. The technical process of doing so is easy, though prosecutors would need to demonstrate probable cause to conduct searches beyond what they were authorized to do so in the investigation of Weiner. Some legal analysts suggested that might present some challenges, though it was hard to assess given the lack of information about what agents had seen. Investigators could also get the consent of the owner to search a device or email account – in this case, depending on the precise circumstances – that would presumably be Abedin or Weiner.

Comey in July announced that he was recommending the investigation into Clinton’s use of a private email server while she was secretary of state be closed without charges. But he said investigators had found classified information on the server and characterized Clinton’s and her aides’ conduct as “extremely careless.”

Provided they get the legal authority to do so, investigators will be looking at whether the newly uncovered emails contain classified information or other evidence that could help advance the Clinton email probe. It is possible, though, that the messages could be duplicative of others already recovered elsewhere or that they could be a collection of benign, personal notes.

The process, former FBI officials have said, could be cumbersome and drag on after the election – particularly if wholly new emails were found. Investigators would have to read those for potentially relevant information, and, if there were questions about their classification, send them to other agencies for review.

Legislators on both sides of the political aisle are likely to raise questions about why the team investigating Clinton’s private email took so long to brief Comey. Clinton and her backers have pushed aggressively for the bureau to release more information about its findings and criticized the agency for making its work public without knowing more. Republican presidential nominee Donald Trump has called the matter “the biggest scandal since Watergate” and suggested, without evidence to support it, that the case against Clinton was now “so overwhelming.”

A Washington Post-ABC News tracking poll found that more than 6 in 10 likely voters said the FBI’s announcement would make no difference in their vote. A little more than 3 in 10 said the news made them less likely to support Clinton, though about two-thirds of those were Republicans or Republican-leaning independents.