Federal court papers show John Harberson, of Carriere, filed the notice Thursday in U.S. District Court in Gulfport.

Harberson and Scott Jenkins Waits, of McHenry, were arrested after officers at the South Mississippi Correctional Institution found a pipe bomb in a vehicle June 1.

Harberson had driven Robin Denell Baker, of Gulfport, to visit an inmate, authorities say.

Harberson told agents he and Waits had built the pipe bombs from aluminum flashlight bodies, shotgun shells, black powder and candle wax. He said they had made a previous bomb and blown it up in a gravel pit near Waits’ home.

Harberson said he forgot the new bomb was in the car when he and Baker drove to the prison for the visit.

Officials say they don’t believe the bomb was intended for the prison.

Harberson’s change of plea hearing is July 31.

Waits has pleaded not guilty.

They were indicted June 25 in U.S. District Court in Gulfport on two counts each of making and possessing a destructive device. Waits also was charged with being a user of controlled substances in possession of firearms.

A trained dog at the South Mississippi Correctional Institution found the bomb. A search also found a machete, two knives, and tobacco in the car, authorities say.

Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives and the Biloxi police bomb squad were called. They took the bomb away from the prison gate and “rendered the device safe.”

After interviewing Harberson, federal agents arrested Waits and searched his home, where they allegedly found bomb-making materials.