The Bucks County man accused of making pipe bombs inside his mother's Warrington home pleaded guilty Monday to illegal possession of an unregistered explosive device.
John Grzyminski was federally charged after police say he built three pipe bombs-- which the bomb squad detonated back in May.
Grzyminski's mother called police to report that she felt threatened by her son. After police left, she found a pipe bomb in the kitchen.
Police came back out to the home along with the Bomb Disposal Unit and the Bureau of Alcohol, Tobacco, Firearms, and Explosives. Bomb technicians found two more pipe bombs in a bedroom and bomb making materials in the garage.
Grzyminski will be sentenced on January 4th.
He faces a maximum sentence of 10 years in prison and fines up to $250,000.
