FBI officials will hand over the first of "tens of thousands" of deleted emails from Hillary Clinton's private server on Friday to the State Department, government lawyers told a court Monday.

Judge Emmet Sullivan of U.S. District Court questioned State Department attorneys on why the agency would not receive the documents until several weeks after the Clinton email investigation had been closed.

"I don't understand the need for all this time," Sullivan said during a hearing Monday on whether Clinton should submit for a deposition in a Freedom of Information Act case.

Agency attorneys said the delay was due to the format of the emails, some of which have been deleted from the multiple servers Clinton used during her tenure.

The case, which was brought by conservative watchdog Judicial Watch, has already forced six of Clinton's top aides to submit for depositions.

"No one has been able to testify under oath about why the system was created," argued Michael Bekesha, a Judicial Watch attorney, about why a deposition with Clinton is necessary.

David Kendall, Clinton's personal lawyer, was present at the hearing, along with two other representatives for the presumptive Democratic nominee.

Judicial Watch's legal team argued evidence uncovered in the case so far suggests the email system was not maintained for convenience, which has been Clinton's stated reason for setting it up.

Bekesha noted that even if the server network had been established initially for convenience, Clinton was repeatedly reminded of her obligations to preserve records under FOIA but chose to avoid communicating on an official account anyway.

Clinton's attorneys have argued that the depositions of her top aides, including Huma Abedin and Cheryl Mills, should be sufficient to address Judicial Watch's lingering questions.

But the legal team for the conservative group has pointed to gaps in the testimony given by members of Clinton's inner circle. None of the six aides who testified could explain how or why the email network was initially set up.

The hearing Monday came as Clinton attempts to pivot from the email scandal a week ahead of the Democratic convention in Philadelphia.

The FBI's announcement earlier this month that she would not face criminal charges for her handling of sensitive material gave Clinton reason to dismiss continued inquiries about her emails as partisan witch-hunting. But the FBI's claim that Clinton and her team were "extremely careless" in their handling of classified information could cause political problems for Clinton.

Judicial Watch lawyers said they were not engaging in a politically-motivated search. The watchdog group offered to limit their deposition of Clinton, should one be permitted, to three hours and to focus on a narrow set of questions related to the former secretary of state's FOIA obligations.

Bekesha said officials at the State Department have not denied that Clinton has personal knowledge of the operation of the email network.