Karl Rove has been questioned by House Judiciary Committee lawyers on the role he may have played in politically motivated firings of U.S. attorneys.

Committee Chairman John Conyers confirms the former Bush White House official made the closed-door appearance Tuesday. The committee has been trying to determine who created the list of federal prosecutors who would lose their jobs. Conyers has said he suspects the trail led to the White House, but the Michigan Democrat has not been able to prove it.

Former President George W. Bush asserted executive privilege for Rove and former White House lawyer Harriet Miers and refused to let them testify. But the committee reached an agreement with Rove's lawyer earlier this year that calls for Bush's top political adviser to testify, Conyers says "under the penalty for perjury."

Nine U.S. attorneys were fired. An internal Bush Justice Department investigation concluded that political considerations played a part in at least four of the dismissals.