An inmate with three months left to serve on his sentence escaped from the minimum security unit at the Monroe Correctional Complex, the state Department of Corrections said.

Corrections officers and local police are looking for Brandon Musto, 37, who turned up missing at the 9 p.m. Wednesday count.

He apparently went over a fence, although officials are checking video as they investigate exactly how he got out and whether he had any help, spokesman Chad Lewis said.

Searchers believe they know where Musto may be found, but they won't say publicly so as not to tip him off, Lewis said.

Musto began serving time in September 2011 for a for vehicular assault conviction in Thurston County and was scheduled for release in February 2013.

Why would a short-timer risk several more years in prison that could come with an escape conviction?

"That might be the first question we ask him," Lewis said.

Only offenders who are within four years of release are kept in the minimum security unit.

"You have a foot out the door, there's little incentive," to escape, Lewis said.

Minimum security is one of five units at the prison complex at Monroe, 24 miles northeast of Seattle. It holds about 460 of the 2,500 offenders in the state's second-largest prison.

Musto is a white man, 5-foot-8, 180 pounds with brown eyes and dark hair. He has tattoos on his right arm and left wrist.