DENVER - U.S. Marshals are on the hunt for a sex offender.

Matthew Caulk has been on the run for about a week and a half. He walked away from a half-way house in south Denver.

Caulk sexually assaulted a girl in Washington state in 2002 and sexually assaulted a missing teen in Jefferson County in 2007.

Crime Stoppers is offering a reward for information that helps police arrest him. You can call crime stoppers at 720-913-STOP.