ANN ARBOR (WKZO) -- A Trenton man was found guilty of manufacturing and possessing a destructive device and other felony charges in federal court in Ann Arbor.

John Kennedy disguised his voice and phoned in a bomb threat to Trenton High School in April of 2011.  He claimed there were four bombs in the school and a teacher located one device in the parking lot.

Authorities say Kennedy later exploded a bomb in the parking lot of a hardware store.  He faces up to ten-years behind bars for each charge and a 250-thousand fine or both.  He will be sentenced on March 5th next year.