David St. Onge, Sr., has been arrested for killing his 88-year-old father, Jack St. Onge of Plymouth Township, Montgomery County.
The dead man's grandson, David St. Onge, Jr., also has been arrested for conspiring with his father to dispose of the body in northern Pennsylvania's Susquehanna County.
Charges against the two men include abuse of a corpse.
Montgomery County District Attorney Risa Vetri Ferman said Wednesday the murder took place inside the victim's home at 3010 Arch St. in Plymouth Township.
The son and grandson also lived at that address.
A news release from the district attorney states David St. Onge, Sr., admitted striking a single blow to his father's head, then conspiring with his son to dispose of the body.
In addition to murder, he is charged with stealing items belonging to his father and selling them. He used some of that money to buy heroin, according to law enforcement officials.
When questioned by police on Tuesday, St. Onge initially said he had no information about his father's whereabouts and denied ever striking or hitting him.
When confronted about inconsistencies in his statement, he told police that on June 10 his father told him he was going to throw him out of the house the next day.
Later that day, he admitted, he struck his father in the back of the head with a flashlight as he passed him on the basement stairs.
After finding no sign of life, he initially put his father's body into a closet in the house and cleaned up the blood.
He removed gold jewelry from the body, which he sold in Philadelphia for $500. He told police he used the money to buy food and heroin. He also took his father's credit cards.
St. Onge then recruited his son, David St. Onge, Jr., to help his dispose of the body.
They bought two traps, duct tape and flashlights at Walmart, wrapped the victim in the tarps, then put the body into the trunk of the victim's 2007 Toyota Corolla and headed upstate on the Pennsylvania Turnpike's Northeast Extension.
Along the way, they stopped to buy a map to help them select what they hoped would be a remote location to dispose of the body.
Last Friday, Pennsylvania State Police responded to a report of a dead body wrapped in tarps and duct tape along the side of State Route 2036, near Route 92 in Gibson Township, Susquehanna County.
The body had been discovered by employees of a logging company.
An autopsy was performed Tuesday by Dr. Gary Ross, a forensic pathologist in the Susquehanna County coroner's office. He was able to identify the victim from the serial number on his pacemaker.
The manner of death was ruled a homicide, but the cause of death remains under investigation.
Ross determined there were several injuries to the back of the victim's head, caused by apparent blunt force trauma with an unknown object.
On Wednesday, the 59-year-old St. Onge was charged with third-degree murder.
He also has been charged with theft by unlawful taking, possessing an instrument of crime, tampering with evidence, conspiracy to tamper with evidence, abuse of a corpse, conspiring to abuse a corpse and providing false information to police.
Ferman reported additional charges may be filed after a coroner makes a final determination on the cause of death.
Both father and son were committed to Montgomery County Prison.
The 20-year-old St. Onge, Jr., has been charged with providing false information to authorities, tampering with evidence, conspiring to tamper with evidence, abuse of a corpse and conspiring to abuse a corpse.