A longtime State Department official said he assumed that then-Secretary of State Hillary Clinton was using her personal email to "stay in touch with family and friends", not conduct official business.

In a two-hour deposition with the conservative legal watchdog group Judicial Watch last week, Lewis Lukens also said he offered to set up a "stand-alone" computer for Clinton to check her personal email account, only to be told that she "does not know how to use a computer to do email."

Lukens' testimony was released Thursday, the day after the State Department inspector general released a report criticizing Clinton's email setup, saying that it violated federal records rules and cybersecurity guidelines.

The FBI is investigating possible mishandling of classified information that passed through the server, which was set up in the basement of Clinton's Chappaqua, N.Y. home. Clinton has repeatedly denied any wrongdoing, and did so again Thursday.

"This report makes clear that personal email use was the practice for other secretaries of state," Clinton told ABC News. "It was allowed. And the rules have been clarified since I left."

According to Lukens, he first spoke to Clinton's Chief of Staff Cheryl Mills in 2009 about ways that Clinton could access her personal email without using the State Department's OpenNet system.

In an email released by Judicial Watch earlier this year, Lukens initially suggested a computer that could be "connected to the internet (but not through our system) to enable her to check emails from her desk."

"The reason that I proposed a PC was that it would make it easier for her to log on,” Lukens said in the deposition. “And at that point, as far as I knew, there was no requirement for her to be connected to our system.”

The computer system was never installed. Lukens was told that Clinton could only send and receive email on her Blackberry smartphone.

Because Clinton's State Department office was considered a secure zone, she was unable to bring her Blackberry there. As a result, Lukens recalled "on occasion" seeing Clinton looking at her Blackberry in the hallway outside the secure area.

Lukens, who has been with the State Department since 1989, said he could not recall explicitly discussing Clinton's use of a personal email account with other officials, adding that he assumed she was using "a commercially available email account."

Lukens is the first of at least six named witnesses to be deposed about Clinton's use of a private email server to handle her correspondence during her time as America's top diplomat.

Mills is scheduled to testify on Friday. U.S. District Court Judge Emmet Sullivan ruled Thursday that recordings of her deposition are to be kept under seal over concerns the video might be used "as part of partisan attack" against Clinton.