PORTLAND, Maine — A civilian worker accused of setting a fire that caused $400 million in damage to a Los Angeles-class attack submarine is returning to court, where he faces arson charges that carry a sentence of up to life in prison.

Casey James Fury, 24, of Portsmouth, N.H., who faces two counts of arson at the Portsmouth Naval Shipyard, was scheduled to appear today in U.S. District Court in Portland for a probable cause and detention hearing.

The Naval Criminal Investigative Service says Fury, a shipyard worker, confessed to setting a fire inside the USS Miami while it was in dry dock May 23, as well as setting a second blaze outside the sub on June 16.

Fury, a painter and sand blaster, told NCIS investigators that he was suffering from anxiety and set the first fire to avoid completing his shift stripping paint in the submarine's forward torpedo room, according to prosecutors.

The fire quickly got out of control and the steel hull trapped heat, causing superheated smoke and a stubborn fire that took more than 100 firefighters to douse.

It remains to be seen whether the nuclear-powered sub will be repaired or scrapped.

An affidavit in federal court indicates Fury walked with investigators through another Los Angeles-class sub, the USS Pasadena, where he demonstrated where he'd set fire to rags on a bunk bed before returning to his post in the torpedo room.

By the time the fire alarm sounded, the smoke in a passageway was so thick that Fury and a co-worker had to find another route to safey, departing through an "escape trunk" farther back on the submarine, the affidavit said.

The submarine was undergoing a 20-month overhaul at the Navy shipyard in Kittery, Maine. The fire was confined to forward compartments and did not reach the back of the submarine where the nuclear propulsion components are located.

Fury said he set the second fire outside the submarine at the dry dock cradle after a text-message exchange with an ex-girlfriend about a man she had started seeing, according to the affidavit. That fire caused little damage.