Police called the house a "drug nexus" and said that the boys were killed in a drug deal gone bad. They arrested the boys' parents, Rohan and Cynthia Bennett, on numerous drug charges after a large amount of narcotics and cash were allegedly found in the home.
Gonce, of Upper Darby; Terrence Seldon, 26, of Philadelphia; and Michael Holmes, 28, of Philadelphia, allegedly conspired to commit the robbery and killings, according to police.
Just two days before the slayings, Gonce and Seldon committed a home invasion at the New Orleans Park Apartments on Upper Darby's South Avenue, said Upper Darby Police Superintendent Michael Chitwood.
Gonce, who lived in the apartments, wore a mask when he and Seldon broke into a unit, tied up the man inside with an electrical cord and held a gun to his head demanding money, police said.
Problem was, the man inside wasn't the resident; it was his brother, Chitwood said. The intruders didn't get any cash, but they did walk away with a TV, credit cards, a computer and other items, according to police.
After the killings two days later, Seldon remained in Philadelphia but Gonce fled to the house of a family friend in Baltimore County, Chitwood said.
Gonce told the friend that he had been set up and needed a place to stay, according to Chitwood.
While hiding out at the house, Gonce allegedly raped two girls between ages 12 and 14 who were staying there and he killed the homeowner's cat, Chitwood said.
Upper Darby police, who had already identified Gonce and Seldon as suspects in the home invasion, then received information that Gonce was hiding in Baltimore, Chitwood said. They contacted Baltimore County police, who arrested Gonce at the house on Aug. 7. Gonce fled but was found hiding nearby in a trash can, Chitwood said.
When he was taken in for questioning, Gonce reportedly admitted to the home invasion, the rapes and the double murder in Overbrook, Chitwood said.
Gonce remains in Baltimore County, where he is charged with three counts of rape. He is awaiting extradition to Philadelphia.
During police interviews, Gonce fingered Seldon as his accomplice, Chitwood said.
On Friday, Seldon was picked up on the Upper Darby warrant at his house on Dorel Street near 66th, in Philadelphia, police said. He was taken in for questioning by Philadelphia police and admitted his role in the Overbrook slayings, according to Chitwood.
Holmes was taken into custody last Wednesday, though the circumstances of his arrest were not immediately clear. He's believed to have been the alleged getaway driver in the slayings.
Philadelphia police spokeswoman Officer Tanya Little confirmed the arrests of Gonce, Seldon and Holmes in connection with the Overbrook slayings.
Contact Stephanie Farr at firstname.lastname@example.org or 215-854-4225. Follow her on Twitter @FarFarrAway. Read her blog at PhillyConfidential.com.