William A. Celtruda is arraigned Aug. 21 in New London Superior Court on charges linked to a fire that destroyed a house on Library Street in Mystic in late July.

Probationary Mystic firefighter William A. Celtruda confessed that he set fire to an unoccupied Library Street house on July 25 to prove himself to other firefighters, according to Groton Town Police.

Celtruda, 21, told police he and other firefighters had been drinking beer at the Hoxie Fire Station in the hours before he set fire to the structure at 23 Library St. The firefighters teased him because “he had never fought a real fire,” Celtruda said.

So he drove to the house, stuffed paper towels inside a rolled-up carpet on the front porch and used a lighter to ignite them. He said the carpet ignited immediately and the fire became “pretty intense.” He drove back to the fire station to wait for the fire call and was on the first fire engine to arrive at the scene.

An arrest-warrant affidavit unsealed this week in New London Superior Court details the investigation town police conducted in the aftermath of the fire that destroyed the historic house. Owned by Gretchen Chipperini, the century-old structure had been under renovation for years and was not insured at the time of the fire.

Celtruda, of 286 Judson Ave., was charged with first-degree arson and first-degree criminal mischief. He was subsequently charged with setting fires on Aug. 12 to houses at 115 Little Gull Lane and 19 W. Mystic Ave. He is being held at Corrigan Correctional Institution in lieu of $350,000 bond and is scheduled to appear in court again on Sept. 8.

Celtruda had been a volunteer for the Mystic Fire Department for about six months and is part of a family with longtime connections to the department. According to the police affidavit, he and Kyle Hilbert, who is the nephew of fire chief Fritz Hilbert, spent the night at the fire station with three other firefighters. In an Aug. 14 interview at the fire station, Hilbert told police he and Celtruda drank beer in the meeting room while the others slept in the bunk room.

Hilbert said he and Celtruda drank until about 1 a.m. and that he was “a little intoxicated.” He said he and Celtruda were talking about past fires and that Celtruda said “how cool it would be to have a fire.” Hilbert said he did not want a fire because the two had been drinking. At about 2 a.m., the two men broke a plastic table in the meeting room. As they were taking it outside, they decided to set it on fire. They used solvent cleaner and acetone to set the fire, finishing up about 3:30 a.m.

They then went to the bunk room, Hilbert said, but Celtruda was so loud the other firefighters told him he could not sleep there.

Hilbert said he went to bed about 4 a.m., and the next thing he knew firefighter Nick Allyn was waking him up for an alarm. He had a hard time waking up, Hilbert said. He drove Engine 52 to the Library Street fire, which had been called in around 5 a.m. Celtruda was also aboard Engine 52.

Celtruda, interviewed by police a day after they spoke with Hilbert, said he was upset after being told he could not sleep in the bunkroom. He said he was driving home in his Ford Ranger when he passed 23 Library St., which he knew to be unoccupied.

”He decided that he was going to set the house on fire to prove himself to the other firefighters,” according to the affidavit.

The Mystic Fire Department called on several departments to help fight the fire. As the crews worked, parts of the roof, wraparound porch and interior first floor collapsed without warning, according to the affidavit. The fire was brought under control after nearly five hours.

The Little Gull Lane and West Mystic Avenue homes that Celtruda is accused of torching were both occupied. The fire on Little Gun Lane originated in the attached garage and was called in at 3:06 a.m. Police said they found items at the scene that linked Celtruda to the fire, including a paper bearing the name “Celtruda.” The West Mystic Avenue fire, called in as crews responded to the other blaze, originated on the exterior of the house.

The arrest warrants detailing those alleged crimes will remain sealed until Sept. 9.

K.FLORIN@THEDAY.COM