The coroner made that ruling after examining the victim, 52-year-old Barry Groh of Park Avenue in Quakertown.
An autopsy performed Tuesday found that Groh had suffered a single gunshot wound. The bullet entered his upper left arm and then entered his chest, killing him, the coroner said.
The circumstances surrounding this death remain under investigation. There is no word on an identity of possible suspects.
According to investigators, man killed a deer then called his wife to get their son to help carry the animal. By the time the son arrived, the man had been shot.
The man's body was spotted Monday morning in a heavily wooded area along the 1100 block of California Road in Richland Township near Quakertown, Pa. He was partially submerged in Tohickon Creek. His legs and boots were visible.
Next to the man was a large 8-point deer that was also dead, according to authorities.
At first, authorities thought the hunter had a heart attack trying to bring the deer out of the woods. It was only later that they discovered the gunshot wound.
Sgt. Richard Ficco of the Richland Township Police told Action News: "The deer that he apparently shot was lying right next to him. It looked like he was in the process of dragging it out of the woods. They were actually both found just along the waterway."
The victim's shotgun was found about 15 feet away, leaning against a tree.
The Bucks County D.A., the Pennsylvania State Game Commission and others are on the case.
The rugged terrain made investigating the scene difficult. Much of the personnel and their equipment needed for the investigation had to be brought to the scene by all-terrain vehicles.