Shana Decree, 45, was arraigned on five counts of murder and conspiracy charges around 4 a.m. Her 19-year-old daughter Dominique, also believed to be responsible in the murders, is expected to be arraigned on the same charges later in the day.
Action News is told the family is known to the Bucks County Children and Youth Social Services Agency.
According to the affidavit of probable cause, the agency did a welfare check at the Robert Morris Apartments in the 200 block of West Bridge Street in Morrisville on Saturday, but when no one answered, a worker left a card.
Representatives returned to the apartment for an unannounced visit around 4 p.m. Monday and contacted a maintenance worker at the complex.
When the maintenance worker gained access to the apartment, he found Shana and Dominique Decree in bed. The worker reported that the two seemed disoriented and the apartment was in disarray. Police were called to the scene and both were taken to the hospital.
According to the affidavit, arriving officers saw furniture upended in the apartment, along with broken glass and clutter. The Children and Youth representatives told police the apartment was not in disarray during their last visit in early February.
Police initially saw four bodies in a small bedroom. The fifth was later discovered underneath another body.
The five family members killed have been identified as: Shana Decree's children, Naa'Irah Smith, 25, and Damon Decree Jr., 13, both of Morrisville; Shana's sister, Jamilla Campbell, 42, of Trenton, New Jersey; and Campbell's 9-year-old twin daughters, Imani and Erika Allen.
"This is a terrible tragedy. I just spoke with the family of the five of the deceased and we're all heartbroken," Bucks County District Attorney Matthew Weintraub said during a Monday night press conference.
The affidavit says Shana and Dominique Decree were read their Miranda rights in the emergency room of the hospital and both spoke to police without an attorney present.
Authorities say Dominique had visible injuries to her neck and, at first, denied knowing what happened. She reportedly claimed that an unknown male hurt her and she kept repeating she wanted to die.
Shana also first denied knowing what happened, according to the affidavit, claiming her sister's boyfriend and two unknown males came into the apartment and killed everyone except her and her daughter.
Dominique separately then echoed claims about her aunt's boyfriend and two unknown males.
The affidavit indicates that later, Shana told police everyone in the apartment, including the 9-year-old twins and 13-year-old, wanted to die and were talking about suicide.
According to the affidavit, Dominique told police how each person was killed. She said her mother and Campbell killed the others and then she killed Campbell through choking.
Authorities were searching for Jamilla Campbell's 17-year-old son, Joshua Campbell, to ensure his safety.
They located him Tuesday morning in Willingboro. He is not considered a suspect.