David St. Onge Jr., the 20-year-old son of David Sr. and grandson of the victim, was charged with five misdemeanor counts, including abuse of a corpse and tampering with evidence, according to a court document.
The District Attorney's Office said St. Onge Sr. admitted to investigators that he struck his father once on his head. No other details were given.
Authorities said earlier Wednesday that they were investigating the killing of Jack St. Onge, and that they had determined that it occurred at his Arch Road home.
The body was found Friday morning in rural Susquehanna County by workers clearing brush, said Susquehanna County District Attorney Jason Legg.
"My understanding is [the victim's body] had been there for some time." Legg said.
An autopsy performed Tuesday by that county's coroner concluded that the death was a homicide. Police said they identified the body through a pacemaker.
The Susquehanna County District Attorney's Office is not a part of the investigation at this time. "The victim had no connection in my county at all that we can tell," Legg said.
On Arch Road, residents said they mainly knew only the people who lived beside them, not those across the busy thoroughfare off Germantown Pike.
Marian Wilbar, though, said she had lived next door to Jack St. Onge since 1966, the year after the Wilbars bought their house.
"He was a good neighbor" who helped with shoveling, she said.
St. Onge enjoyed playing golf until recently and once in a while came over for dinner, she said.
His wife died about six or seven years ago, Wilbar said, and this past winter St. Onge's son and grandson moved in with him.
"He was a good man and highly intelligent," she said. "I'm upset. I'd like to know what really happened."