Foley, a Florida Republican, resigned last month after reports surfaced of an exchange of sexually suggestive e-mail and instant messages with young male pages. Pages are high school juniors from around the nation chosen by congressmen and senators on merit to serve one semester in Congress, running messages and doing other errands for members.
Jeff Trandahl answered closed-door questions from the House Ethics Committee on the Foley situation for four hours Thursday, the New York Times said.
Trandahl refused to comment after his testimony but he reportedly told of informing the speaker's office of concerns Foley seemed to be spending too much time with young pages.
Investigators see Trandahl's account as crucial in determining if House Speaker J. Dennis Hastert knew of Foley's conduct, the Times said.