A conservative watchdog group published on Monday the third in a series of transcripts of interviews with current and former State Department staff who may have had knowledge of Hillary Clinton's private email use.

The deposition of Stephen Mull, which was conducted Friday by Judicial Watch, revealed Clinton struggled at times to set up secure phone lines on which to discuss potentially classified information.

But Mull, a high-level State Department official during Clinton's tenure, told attorneys Judicial Watch that he did not recall the answers to many of their questions about the former secretary of state's personal server.

Cheryl Mills, Clinton's former chief of staff, and Lewis Lukens, another State Department official, have already been deposed by the watchdog group, which has been authorized to question members of Clinton's inner circle as part of a Freedom of Information Act lawsuit over records from Clinton's office.

Bryan Pagliano, Clinton's former information technology specialist, was scheduled for a deposition Monday before his lawyers informed the court last week that he intended to invoke his Fifth Amendment rights and decline all question

Judge Emmet Sullivan of U.S. District Court, who is presiding over the case, responded by requiring Pagliano's legal team to divulge the details of an immunity deal he reportedly struck with the Justice Department in exchange for his testimony.

During his deposition, Mull was presented with an email in which he had mentioned to Clinton confidante Huma Abedin and other senior State Department officials that Clinton's "personal email server is down."

Although he admitted that, by the time he sent the email in question in Aug. 2011, he was aware Clinton used a private server, Mull said he could not recall when or how he learned of the server's existence.

In the same email, Mull, who served as executive secretariat during part of Clinton's tenure, mentioned that he could set up an email address on Clinton's BlackBerry phone but warned that it could be subject to FOIA.

Mull said he could not recall why he discussed with Clinton aides the possibility that Clinton's emails would be subject to open records laws.

Mull noted he had spoken with the State Department inspector general about email use. The agency's inspector general released a scathing report late last month that indicated Clinton had violated State Department policy by setting up a private server.