ALLENTOWN, Pa. (AP) — The district attorney says an Pennsylvania man used a homemade, high-pressure air gun to fatally shoot a neighbor with whom he had an affair.

Thirty-five-year-old Josef Raszler was charged Wednesday with criminal homicide in the Sept. 13 shooting of 46-year-old Stephanie Roof. She was shot with a homemade metal projectile about 1 a.m. in the driveway of her home across the street from Raszler’s in Lower Macungie Township.

Raszler’s public defender wasn’t immediately able to comment Thursday. Police say Raszler acknowledged a romantic relationship with Roof that she ended in the summer of 2015, angering him.

Lehigh County District Attorney Jim Martin says investigators haven’t found the weapon Raszler allegedly used, but they have evidence he researched making it and practiced with it at his parents’ lake house days before Roof’s killing.