They found 38-year-old Gerald "Skip" Tyrone Murphy in an upstairs bedroom and he told them he was armed with a gun and explosives and had three children with him, Mercer County Prosecutor Joseph L. Bocchini Jr. said. Officers noticed one of the dead victims before they retreated from the second floor and rescued Stevens' 19-year-old son from the basement, who said he hadn't seen her or his siblings since about April 24.
Homes on the surrounding block were evacuated as a precaution, and police tape cordoned off the street in front of the house. A SWAT team was called, and an arson bomb unit was also on the scene. Police said Murphy could be seen from a window holding a black handgun.
Police remained in contact with Murphy throughout the standoff and passed food into the home through an upstairs window, state police Col. Rick Fuentes said. Murphy kept the captives with him inside the roughly 10-foot-by-11-foot bedroom throughout the standoff, authorities said.
As the standoff stretched into a third day, officers entered the home around 3:45 a.m. Sunday after noting Murphy's "deteriorating state of mind" and deciding it was necessary to enter to help ensure the captives survived, Fuentes said. An officer shot Murphy because he was threatening one of the children, he said.
Murphy was taken to a hospital and later died of his injuries. No law enforcement personnel were injured during the standoff or the confrontation with Murphy.
"This was a very complex matter, considering the space (where the hostages were) and that three children were involved," Fuentes said. "Our mission over those 37 hours was to save innocent lives."
Authorities found the bodies of Stevens and her 13-year-old son in separate bedrooms. Stevens' body was in an advanced state of decomposition, and police said she and her son may have been killed two weeks ago. Police didn't say which of the bodies they had seen inside the home Friday afternoon.
Three of Stevens' children an 18-year-old woman, a 16-year-old girl and a 4-year-old boy were rescued and taken to a medical center for evaluation and treatment. Murphy had abused and assaulted the captives, Bocchini said.
Murphy and Stevens had been dating for a few months, and both lived in the house, police said. He was not the father of any of her children.
Authorities wouldn't comment on a possible motive or say how the victims died, citing the ongoing investigation. They also would not say whether any bombs or other explosives were recovered at the residence.
Attempts to contact the victims' relatives and neighbors were unsuccessful on Sunday.
Murphy had a long criminal history including convictions for aggravated assault and criminal conspiracy, Bocchini said. He had previously been arrested for robbery and weapons offenses and child endangerment. He also had an arrest warrant in Pennsylvania for failing to register as a sex offender.