Credit: US Marshals

Authorities are hoping the public can help locate a convicted sex offender who is on the run.

Matthew Caulk, 46, failed to register as a sex offender in Colorado and is now wanted by the U.S. Marshals for violation of federal supervised released. He failed to show up at a Denver halfway house, after which a federal warrant for his arrest was issued on Feb. 15.

Caulk currently has two sexual assault convictions, including one in Lakewood, Colo. in 2007, when he sexually assaulted a 15-year-old girl. That assault was committed while Caulk was on the run; it was later discovered he was accompanied by a runaway underage girl while attempting to elude authorities. He was located after he was featured on America's Most Wanted.

Caulk was also convicted for sexual assault on a 13-year-old in 2002.

Caulk is 5-foot-9 and 175 pounds, bald with hazel eyes. He has tattoos on his abdomen, chest and left shoulder.

If you have any information on Caulk's whereabouts, call the U.S. Marshals at 1-877-WANTED2 or Metro Denver Crime Stoppers at 720-913-STOP.