The body of a Fort Drum soldier who was last heard from on Thursday night in upstate New York has been found in a remote part of New Jersey, and the authorities said on Sunday that they had arrested a fellow soldier in connection with his death.

The soldier who was reported missing, Cpl. Hayden Allen Harris, 20, was meeting someone in Watertown, N.Y., for some type of vehicle transaction when he was last heard from, the Army Criminal Investigation Command said in a statement. “According to law enforcement officials, foul play is suspected,” it said.

Gregory Mueller, first assistant prosecutor in Sussex County, N.J., where the body was found, said a fellow soldier from Fort Drum, Pfc. Jamaal Mellish, 23, was arrested in Jefferson County, N.Y., over the weekend. Private Mellish was expected to be charged with murder, kidnapping and possession of a weapon for unlawful purposes, after which he was expected to be extradited to New Jersey, Mr. Mueller said.

Corporal Harris was posthumously promoted from the rank of specialist, the Army said. It was not clear on Sunday how the encounter had turned deadly. Officials said they expected to release more information Monday.

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.

Mr. Mueller said he was not aware of any connection that Private Mellish had to Byram Township.

Corporal Harris of Guys, Tenn., joined the Army in March 2019 and arrived at Fort Drum in July 2019 after he completed his training at Fort Benning, Ga., according to a statement from Fort Drum and the 10th Mountain Division. In that time he earned several awards and decorations, including the National Defense Service Medal, the Global War on Terrorism Service Medal and the Army Service Ribbon, the Army said.

“We are devastated,” Brig. Gen. Brett T. Funck, the acting senior commander of Fort Drum and the 10th Mountain Division, said in the statement. “His death is a tremendous loss for his loved ones, this Division and our nation.”