The two soldiers had met to discuss a disagreement over a 2017 Chevrolet Silverado pickup truck, Mr. Mueller said. The authorities believe Private Mellish abducted Corporal Harris, driving him in the Silverado from Watertown, which is southwest of Fort Drum and about 71 miles north of Syracuse, to Byram Township, N.J., he said. A third person, a juvenile whose involvement was still under investigation, was also in the truck, Mr. Mueller said.
Members of the township’s Fire Department called the police after they spotted papers and shoes in a cul-de-sac on Saturday, the town’s mayor, Alex Rubenstein, said in a telephone interview on Sunday night. At the time they saw the items, the firefighters were escorting a man dressed as Santa Claus in a decorated fire truck as he handed out candy canes to children, Mr. Rubenstein said.
The police found Corporal Harris’s body in the woods behind the homes in the cul-de-sac, Mr. Mueller, the prosecutor, said. Officials believe Corporal Harris was killed in the woods, where his body was found with a gunshot wound, Mr. Mueller said.
Mr. Mueller said he was not aware of any connection that Private Mellish had to Byram Township.
Mr. Rubenstein said the killing was “very unusual” for Byram Township, where, to the best of his knowledge, there had not been a murder for nearly a century. He described the township as a “small, rural bedroom community” of about 8,000 people about 50 miles west of the George Washington Bridge.
Residents, he said, were “really mystified by how whatever was happening found its way to our town.” The area where the body was found — “a dead-end street with only a number of houses on it” — is “deep inside” a housing development, Mr. Rubenstein said.