(KRON) -- A Napa man was arrested on Friday after deputies found materials that can be used to make explosives, the Napa County Sheriff's Office said. The suspect had previously been convicted of possessing pipe bombs. NCSO's SWAT team served a search warrant at the home of 31-year-old Justin Fisher on the 300 block of Coombs Street at about 7 a.m. SF woman attempted to steal cart full of items arrested: PD Fisher was being investigated after he bought chemicals known to be used for making bombs, NCSO said. His 2019 conviction was for having materials used to make bombs. The search on Friday discovered substances used to make explosives. "Detectives believe Fisher possessed these items with the intention of making more destructive devices," NCSO said. In 2019, Fisher was driving on State Route 29 in American Canyon when NCSO's bomb squad found two pipe bombs, explosives and drugs in his car.