Sen. Lamar Alexander (R., Tenn.) has replaced his chief of staff after learning the staffer's home was being searched as part of a child- pornography investigation.

Alexander said in a statement Wednesday that it would be up to the courts to judge Ryan Loskarn, but "under these circumstances, he cannot continue to fulfill his duties as chief of staff."

A Justice Department spokesman said in a statement that Loskarn was arrested based on probable cause for possession and distribution of child pornography.

Video taken by WJLA-TV showed Loskarn being led from his Washington home by Postal Inspector police. He remained in custody pending an expected Thursday hearing in federal court in Washington. - AP