Then-Secretary of State Hillary Rodham Clinton checks her Blackberry in 2011. (Kevin Lamarque/AP)

A senior State Department official who oversaw executive operations during Hillary Clinton’s tenure as secretary from 2009 to 2013 told lawyers in a civil lawsuit that he was aware of her private email server, but had no reason to think it was used for government business, according to a transcript released Monday.

“Your question is based on the assumption that I knew that someone was conducting government business, and I -- I don’t have a basis to make such a judgment,” Stephen D. Mull, said in a sworn deposition. Mull was executive secretary of the department from June 2010 to 2012 and since September is its lead implementation coordinator for the U.S.-Iran nuclear deal.

Mull also told lawyers for the conservative group Judicial Watch that he did not recall informing top Clinton aides in August 2011 that emails sent from a department-issued Blackberry would be subject to public records requests.

Mull joined a list of top State officials who have shed little new light on the workings of Clinton’s email set-up which is the subject of a Judicial Watch lawsuit into whether it thwarted federal open records law.

Mull, an ambassador to Poland from 2012 to 2015 who played a key role in early negotiations with Iran, expressed no opinion on whether it was a mistake by the department to let Clinton and top aides leave office in early 2013 without preserving more than 30,000 government-related emails. They and their lawyers later reviewed and selected the emails to be returned after the existence of Clinton’s private server was reported last year.

“If I were aware that any Secretary of State while I was serving as Executive Secretary were not aware of [record-preservation] responsibilities, I -- I would have taken steps within my power to inform them of that,“ Mull said in his deposition.

But, he added, “I think it’s difficult with hindsight to say something was a mistake, if a person didn’t have the knowledge at the time of what was going on.”

Mull answered questions for more than three hours Friday at a deposition attended by eight lawyers for the government and Judicial Watch, days after deposition appearances by former Clinton chief of staff Cheryl D. Mills and Lewis A. Lukens, a former administrative official.

U.S. District Judge Emmet G. Sullivan last month allowed depositions of a half-dozen officials in a lawsuit over Judicial Watch’s request for information about Abedin’s employment arrangement. Under Secretary Patrick Kennedy and Clinton aide Huma C. Abedin, now vice chair of Clinton’s presidential campaign are set to appear at the end of June.

Sullivan postponed Monday’s scheduled deposition of a former State and Clinton-campaign staffer who helped set up the server, Bryan Pagliano, while the judge seeks more information about the aide’s immunity agreement with federal prosecutors in a criminal investigation into the handling of classified information.

In the civil suit, Sullivan has focused the inquiry on whether the department’s failure to preserve official agency records on Clinton’s server was evidence of bad faith in complying with the federal Freedom of Information Act known as FOIA.

The picture emerging from transcripts posted publicly so far is murky.

Last week, Mills said during her deposition that she did not recall any discussion either of Clinton possibly using a State Department account or her emails’ availability under FOIA, but that she believed Clinton’s emails would be subject to the law because they would be retained by recipients who used official government addresses.

Mills said she did not think about emails that were sent to non-government addresses not being retained, but regretted it and “wish I had.”

Still, Mills said she did not recall ever discussing FOIA requirements, even when shown the August 2011 email chain from Mull, concerning his response to reports of Clinton’s communications problems, including “possibly because of her personal server is down[sic].”

“We will prepare two versions for her to use, one with operating State Department email account which would mask her identity but which would also be subject to FOIA requests,” Mull wrote.

Mull said he not recall the communication, or the circumstances behind it.

“So you don’t recall why you wrote this sentence?” Judicial Watch lawyer Michael Bekesha asked.

“Today I don’t, no,” Mull said.

Mull said he could not recall any conversations about Clinton’s server during his time as executive secretary, nor any conversations or concerns that her emails were not being searched in FOIA requests.

Mull said if he had discussions regarding Clinton’s use of a Blackberry, it would have been with his administrative and logistics unit’s “mobile solutions” technical support team.