Four of the five family members found dead inside a cramped Morrisville apartment last month in an apparent murder-suicide were asphyxiated and a fifth victim was strangled, the Bucks County Coroner’s Office said Friday.

The causes of death for Damon Decree Jr., 14; Erika and Imani Allen, both 9; and Naa’Irah Smith, 25, were ruled to be asphyxiation. Jamilla Campbell, 42, was killed by strangulation.

All five deaths were ruled to be homicides, a spokesman for the coroner’s office said Friday.

Shana Decree, 46, and her daughter Dominique Decree, 19, have been charged with the murders and are awaiting a preliminary hearing in the case, tentatively scheduled for next month in Doylestown.

“The investigation into these murders continues with one goal: justice for five people killed in Bucks County. We are committed to seeking justice for Erika, Imani, Damon, Naa’Irah and Jamilla,” said Deputy District Attorney Christopher W. Rees, who is assigned to the prosecution. “We recognize that the public is very interested in this story, and we are grateful for the community’s support. In deference to this overwhelming tragedy, we ask that everyone respect the families’ privacy as they continue to mourn their loved ones.”

A case worker with Bucks County Children and Youth Social Services found all seven inside a basement unit in the Robert Morris Apartments on Feb. 25.

The five victims were found lying together in a bedroom inside the home. Their bodies were so closely grouped that investigators initially believed only four people had died.

The mother-and-daughter suspects were in the apartment as well, reportedly lying “disoriented" in another bedroom, authorities said.

They told police that “everyone at the apartment ... wanted to die,” and confessed to strangling Smith, Shana’s older daughter; Damon Decree, her son; as well as Campbell, Shana’s sister; and Campbell’s twin daughters.

They each face five counts of criminal homicide and conspiracy, and remain in the county prison without bail.

Authorities, who continue to investigate, said they knew of no motive for the quintuple homicide, a crime that Bucks County District Attorney Matthew Weintraub has called an “unspeakable tragedy.”

Relatives told The Inquirer that in the weeks before the grisly discovery, the group had become isolated, cramming into Shana Decree’s apartment and cutting themselves off from the outside world. In the brief texts and phone calls, the family in Morrisville spoke of seeing “demons" all around them.

Ronald Smith, Naa’Irah’s father, said the 25-year-old had recently moved in with her mother, despite having her own apartment nearby with her fiance. After a frantic trip north from Maryland to check on his daughter, Smith said she would only talk to him briefly at the door of the Morrisville apartment.

She seemed meek and timid, a departure from her usual demeanor, Smith said. And she told him she needed to "make herself right before going through the pearly gates,” saying the world was going to end by March 1.

“It was like a switch was flipped,” Smith said last month. “I talked to Naa’Irah all throughout the month of January, and then nothing.”

During that self-imposed isolation, the family had attracted the attention of Bucks County Children and Youth. The caseworker who stumbled on the bodies had visited the apartment on Feb. 5, and had tried to contact the family again on Feb. 23.

Sources familiar with the investigation said the caseworker was sent to check on the family at the request of officials at Morrisville Junior/Senior High School. The school’s principal called the agency on Feb. 1 after Damon Decree had been absent for several days and his mother did not return officials’ calls.

Police said Campbell’s daughters were registered for school in Trenton, but had not been attending in the weeks before their deaths.

Officials at the Morrisville School District said last month that Damon Decree had missed nearly 10 days of school in February. The district had been notified by Shana Decree that she wanted to remove her son from the school and begin homeschooling him, and officials were in the middle of making arrangements for that when the boy and his relatives were discovered dead.