PORTLAND, Maine - After agreeing to plead guilty Tuesday to setting two fires aboard the U.S.S Miami, the former civilian painter charged with the crimes could serve about 20 years in prison and pay up to $500 million in fines and restitution.

Casey James Fury, 24, who worked at Portsmouth Naval Shipyard for two years, faces the two counts of arson after he confessed to setting a four-alarm fire aboard the $900 million Los Angeles Class submarine May 23 and a smaller fire in the dry dock June 12.

Investigators determined Fury, who served as a painter and sandblaster, started the two fires because he was anxious and wanted to leave work.

Fury, who has been in custody since his arrest July 22, and his attorney, David Beneman, signed the agreement to plead guilty Tuesday with Thomas Delahanty, U.S. Attorney for the District of Maine, and Assistant U.S. Attorneys Darcie McElwee and James Chapman.

Per federal statute, the first arson charge could keep Fury in prison for the rest of his life if he is found guilty at trial, and the second count has a maximum penalty of 25 years.

As part of the plea agreement, Fury could be imprisoned no less than 188 months - just over 15.6 years - and no more than 233 months - about 19.6 years, according to court records.

"Should the court reject this recommendation of the parties, the defendant shall be permitted to withdraw his plea, and either party shall be permitted to withdraw from this agreement," according to the plea agreement.

Fury could be fined up to $500,000 for both charges to pay for the "cost of repairing or replacing any property that is damaged or destroyed, whichever is greater," according to court records.

He would also have to pay a special assessment of $200 for both charges and provide "an amount of restitution payable to the victims of the offenses in an amount to be determined by the court," according to court records.

The victims in the case include the U.S. Navy as well as seven firefighters and sailors who were injured during the first fire, which took 12 hours to extinguish.

"The parties have not agreed on the amount of restitution that should be ordered," according to the agreement, which also stated Fury is aware the amount could exceed $400 million.

While repairs to the Miami, which has been in dry dock since March, are under way at the shipyard, the U.S. Navy estimates the damage to be around $450 million.

Both Fury and the state may "present evidence and make arguments regarding the appropriate amount of restitution," according to the agreement.

If Fury fails to comply with the terms of the agreement, the government can "fully prosecute" him on all charges and use all statements, including ones made as part of the agreement process, according to court records.