At a news conference Wednesday evening in Northampton Township, First Assistant District Attorney Gregg Shore disclosed the death of suspect Daniel Kenneth Mooney from an apparent drug overdose.
Shore said he is confident that it was Mooney who killed Tyler Christopher Roy, 28, and his wife, Christina Celenza Roy, 27, in their home the night before he died.
"Based upon our evaluation of the evidence, our team is unequivocally convinced that he killed the victims and that he acted alone," Shore told reporters.
The bodies of the Roys had been found Tuesday morning on the upper floor of their split-level home at 26 Kitty Knight Drive in the Churchville section of Northampton Township.
Investigators believe they were murdered sometime overnight, and that the killer had stolen Tyler Roy's 2016 Ford Edge SUV.
The vehicle was found, along with Mooney's cell phone, early Wednesday morning in Northeast Philadelphia. By that time, unknown to investigators, Mooney already was dead.
Mooney had been taken to Temple University Hospital's Episcopal Campus in Philadelphia after suffering an apparent drug overdose around 9:30 p.m. Tuesday near Ruth and Clearfield streets in the city's Kensington section. Efforts to revive him failed.
Having arrived at the hospital without identification, Mooney's identity remained unknown until Wednesday afternoon.
Shore had publicly identified Mooney as a person of interest in the slayings during a noon news conference on Wednesday.
Not long after the news conference, Shore said, Philadelphia police called to report that a man fitting Mooney's description had died at Episcopal Hospital. Mooney's identity was confirmed, and police notified his parents and the Roys' parents.
"This tragedy is unfathomable to all of us. We pray for the victims, and pray with the victims' families," Shore said, asking the public and media to respect the families' privacy as they grieve.
Both victims had been stabbed repeatedly and shot, Shore said, most likely by a long gun found in the home that belonged to Tyler Roy.
"It's clear there was a struggle in the upstairs of the home," Shore said.
The specific cause of death will be determined by autopsies that are scheduled for Thursday morning.
Shore said investigators would continue to process the crime scene for forensic evidence which, along with toxicology results from Mooney, might yield at least a partial understanding of how the slayings transpired.
It appeared that Mooney had entered the home through an unlocked door, Shore said, but there was no indication that the killer, whose parents live in the same neighborhood, knew his victims.
Mooney had long struggled with drug addiction, though it is not yet known whether he was under the influence of alcohol or drugs at the time of the murders, the prosecutor said.
The slayings came to light Tuesday morning when a house painter who was working on the outside of the home came inside and found Tyler Roy's body around 10 a.m. He called 911 and responding officers located Christina Roy's body.
The Roys had bought the home in 2016, the year they married, and were in the process of remodeling it.
Tyler Roy worked as a construction estimator, and Christina Roy worked as a photographer, Shore said.
"It's difficult to talk about the victims," Shore said. "It was clear they were building a life for themselves. They would have been very, very productive members of Bucks County's society, and we in law enforcement mourn with their families. This is a difficult end to a very difficult case."
Shore said Mooney's family had cooperated fully with investigators, and "I would be remiss if I didn't mention the cooperation and the prayers that have come from Mr. Mooney's parents to the victims' families as well."
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