Hillary Clinton will soon face questions under oath about the reasons she set up and maintained a private email server during her four years as secretary of state.

Tom Fitton, president of Judicial Watch, told the Washington Examiner that his group is preparing a set of written questions for Clinton as part of the Freedom of Information Act lawsuit that has already extracted hundreds of documents from the State Department.

Fitton said the questionnaire, which Clinton will be forced to complete within 30 days of receipt, will drill down on the Democratic nominee's shifting stories about why she relied on an unauthorized email network.

Clinton once said she set up the server system for convenience, in order to carry just one device for both personal and work-related communications.

After the FBI discovered she used multiple servers and devices, Clinton told investigators she had used private email at the behest of Colin Powell, after the former secretary of state advised her to do so at a 2009 dinner party.

But Powell has since rejected that statement, and said he has no recollection of the conversation with Clinton. The controversial email system was already in place at the time Clinton said she spoke with Powell.