Prosecutors Monday dropped all charges against 38-year-old Jay Byron Bishop, who was arrested Sunday and accused of carrying a firearm in his moped at a federal park during a Patriot Prayer rally.

Bishop had been accused of being a felon in possession of a firearm and carrying a concealed weapon.

"After receiving the reports, we feel the search that revealed the weapon would fail to withstand a motion to suppress in state court,'' said Jeffrey Howes, First Assistant to the Multnomah County District Attorney.

Because the Ruger firearm was located in a locked compartment of Bishop's moped it likely would be thrown out as evidence under Oregon law as fruits of an unlawful search.

Federal officers from the U.S. Department of Homeland Security made the arrest. They also found ammunition in Bishop's backpack and a knife.

The case is being referred back to federal officers and prosecutors, Howes said.

Bishop is a felon having been convicted in 2010 of unlawful use of a weapon and is not allowed to possess firearms.

Bishop's friend told court officials that Bishop suffers from post traumatic stress disorder after an Army injury. Bishop told court authorities that he has a traumatic brain injury, and that using medication is against his religious beliefs, according to court records. The friend also told court officials that Bishop is part of a gaming world called "War Hammer,'' is a certified tattoo artist and is "quiet and like a hermit,'' according to the court documents.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian