SPRINGFIELD, Mass. (AP) – A convicted felon charged with mailing a silencer said Tuesday he has sold chemicals on the Internet that could be used to make explosives.

Michael Crooker, who has spent time in prison for possessing a machine gun, was arrested in June 2004 on charges he had mailed a silencer that could fit on a rifle. Silencers are considered firearms, and it is illegal for convicted felons to possess or mail them.

Crooker is arguing that the silencer was designed for an air rifle, and is therefore not a firearm.

When authorities searched his home, they found materials they said could be used to make explosives and the deadly toxin ricin. Crooker has not been charged with any crimes related to explosives or ricin, but prosecutors have said they expect more charges to come against Crooker in the next few months.

During a federal court hearing Tuesday to argue that the government improperly searched and seized the silencer that he was mailing along with an air rifle, Crooker said he was familiar with making explosives.

When asked by Assistant U.S. Attorney Kevin O’Regan, Crooker said he has sold ammonium nitrate and hydrochloric acid on e-Bay, an Internet auction site.

Crooker said he never used ammonium nitrate as an explosive, but called it “one of the most useful explosive tools they have.”

U.S. District Judge Michael Ponsor scheduled another motion hearing for Nov. 7.