Jacob Sullivan, who was Hillary Clinton’s deputy chief of staff while she was U.S. secretary of state, has confirmed under oath that both he and Clinton used her private, unsecure and unapproved email system for official government business.

It’s not that that’s been a secret.

But the statement was made in a deposition for a lawsuit by government watchdog Judicial Watch.

The organization has been fighting for years to uncover the truth about Clinton’s mishandling of classified information, which former FBI Director James Comey thought unworthy of prosecution despite concluding she had been “extremely careless.”

“A federal court wants answers on the Clinton email scandal and Mr. Sullivan is one of many witnesses Judicial Watch will question under oath,” said Judicial Watch President Tom Fitton. “It is shameful that the Justice and State Departments continue to try to protect Hillary Clinton and the Obama administration on the email scandal.”

U.S District Court Judge Royce Lamberth has ordered Obama administration senior State Department officials, lawyers and Clinton aides, as well as E.W. Priestap, assistant director of the FBI Counterintelligence Division, to be deposed or answer written questions under oath.

The court found Clinton’s mishandling of classified information “one of the gravest modern offenses to government transparency.”

The watchdog previously released Priestap’s statement that the FBI found Clinton email records in the executive office of the Obama White House.

Judicial Watch said its questions centered on whether Clinton “intentionally attempted to evade the Freedom of Information Act by using a non-government email system and whether the State Department adequately searched for records responsive to Judicial Watch’s FOIA request.”

“Sullivan admitted that he had used his personal Gmail account at times for State Department business but denied that he had sent classified information to Secretary Clinton’s unsecured personal system,” the organization said.

Asked about a 2010 email that included classified material, Priestap said, “When I sent this email, my best judgment was that none of the material in it was classified, and I felt comfortable sending the email on an unclassified system. The material has subsequently been upclassified but at the time that I sent it, I did not believe that it was classified.”

He said he didn’t worry about the non-government email because it wasn’t part of his job.

Lamberth’s deposition order includes former the former U.N. ambassador and national security adviser Susan Rice and former deputy of national security Ben Rhodes.

Judicial Watch is seeking “copies of any updates and/or talking points given to Ambassador Rice by the White House or any federal agency concerning, regarding, or related to the September 11, 2012 attack on the U.S. consulate in Benghazi, Libya.”

And it seeks “any records or communications concerning, regarding, or relating to talking points or updates on the Benghazi attack given to Ambassador Rice by the White House or any federal agency.”