TACOMA, Wash. -

A patient at Western State Hospital has been jailed after his mattress was set on fire, he barricaded himself in a utility closet full of cleaning chemicals and threatened to set off an explosion.

Pierce County prosecutors say the patient, Timothy J. Rohn, faces charges of felony harassment.

The News Tribune reports Rohn has a related history.

In 2005, Clallam County prosecutors charged Rohn with second-degree arson. Court records show he was found not guilty by reason of insanity, and transferred to Western State in Lakewood.

In 1988, he was convicted of fourth-degree assault after an incident that involved an attack with unidentified corrosive chemicals.

Hospital spokeswoman Kris Flowers says Monday's incident was related to an ongoing internal investigation of a series of criminal acts.

No one was hurt in the fire, but hospital officials say the damage will take two weeks to clean up.

The next step for Rohn is a hearing to test his competency to stand trial. The hearing is scheduled for July 18.