BANGOR – A federal jury Thursday found a Washington County man who was an officer in a Calais gun club guilty of illegal possession of firearms after a daylong trial.

Peter David Frost, 36, of Meddybemps was indicted last summer for possessing firearms after being dishonorably discharged from the Marine Corps. He enlisted in the Marines in 1987 and was found guilty of assault in 1992 after a military court-martial. He served five years in a military prison.

He faces up to 10 years in prison and a fine of up to $250,000. A sentencing date has not been set and Frost remains free on bail.

Frost testified Thursday that he was not aware he was prohibited from possessing firearms because of his discharge status. He served as second vice president of the Calais Rod and Gun Club, located in Charlotte, until resigning shortly after his arrest.

The defendant also was certified by the National Rifle Association and taught safety courses at the club. He testified that he answered all questions honestly on the NRA forms to become a certified instructor but said that those certifications were rescinded by the NRA after someone sent a copy of a news story about his arrest to the organization.

Frost had 15 firearms in his truck when he was arrested on June 24, 2003, at the Calais Rod and Gun Club. Four more were found at his mother’s residence in Meddybemps where he lives. All 19 were displayed Thursday in the federal courtroom.

Last June, Maine State Police Detective Ken MacMaster posed as a man named David Maguire after going to Massachusetts to legally obtain a driver’s license from that state using a pseudonym. He signed up for a gun safety course at the Calais Rod and Gun Club to meet Frost.

MacMaster then set up a time for Maguire to meet Frost for assistance with a gun purchase. He testified that Frost and his mother, Pamela Ramsdell, met him at the club and showed him the weapons.

The veteran police detective said that he believed Frost would be charged with being a felon in possession of firearms, but the U.S. Attorney’s Office, which prosecuted the case, sought the indictment based on the dishonorable discharge.

Frost used the surname Ramsdell, the name of the man who adopted him, until 2001. That year, he legally changed his name back to Frost to honor his biological father, the defendant told the court Thursday. He denied changing his name in order to possess firearms illegally.

The trial was delayed several times because Frost fired three court-appointed attorneys before hiring Don Brown of Bangor on Tuesday to represent him.

The jury of six men and six women deliberated two hours before delivering its verdict.