COLLIER TOWNSHIP, Pa. (NEXSTAR) — A former neighbor has confessed to fatally shooting a U.S. Postal Service worker in Pennsylvania because he believed the mail carrier poisoned him and his family with cyanide, a federal official said.

Eric Kortz, 53, turned himself in to the Carnegie Borough Police Department on Thursday in the killing of Louis Vignone in Collier Township, according to Stephen R. Kaufman, the acting U.S. attorney for the Western District of Pennsylvania.

Earlier, investigators reporting to the scene found Vignone in his USPS vehicle with multiple gunshot wounds, including one to the head. They also found a firearm and seven spent shell casings in a nearby yard.

Kortz told authorities that he and Vignone were once neighbors and that he believes Vignone and his family poisoned Kortz and his family with cyanide.

Kortz said he found Vignone on his mail route and stopped his van in front of Vignone’s USPS vehicle, according to the U.S. attorney’s office. Kortz then said he “went to put some bullets in him.”

Kortz said he then dropped the gun and drove to the Carnegie Borough Police Department, where he confessed.

He has been charged with murder and assigned a public defender.