Hillary Clinton set up a private server as secretary of state in order to have intimate conversations with her family, California senator and Clinton supporter Sen. Dianne Feinstein said Sunday.

"I've known Hillary for a quarter of a century. Let me tell you what I do think. I think this is a woman who wants a little bit of a private life," Feinstein said on ABC's This Week. "She wants to be able to communicate with husband, with daughter, with friends, and not have somebody looking over her shoulder into her e-mails."

"Having said that, it is what it is, and you know, I don't think we should make a federal case over it," Feinstein said.

Clinton is the subject of an ongoing FBI investigation into her use of a home-brew server as secretary of state. An audit released last week by the State Department inspector general found that information technology officials were not aware of the "scope or extent" of Clinton's email set up, despite her claims to the contrary. Clinton also did not seek legal approval or guidance for her server, according to the report. If officials had been asked, they would not have allowed it due to "security risks."

The audit also found that two State Department information management staffers were told "never to speak of the secretary's personal email system" after "discuss[ing] their concerns about Secretary Clinton's use of a personal email account."

Clinton has said that she used the server out of convenience. She has also said that she did not want personal matters on her work email.

"It enabled her to reach people quickly and keep in regular touch with her family and friends more easily given her travel schedule," according to a factsheet on her website.