Tempe police say a high school senior told police that an improvised explosive device found in the student's home was made by him years ago.
A probable cause statement submitted by police to court officials says 18-year-old Joshua Prater told police he made the device about eight years ago.
According to the statement, Prater also said he didn't know the device was filled with explosive powder, along with match heads and fireworks.
Prater is accused of one count of misconduct involving weapons, a felony.
A cleaning woman found the device inside the home and took it to a fire station on Tuesday. Firefighters notified police, and the bomb squad responded and disabled the device.
Prater attends Marcos de Niza High School.