Decret Sr. stated that he believed that his wife and daughter were involved in worship.
"From my niece, apparently, they dissected a kind of worship that they materialized online," he told the news channel. "I do not know how, what kind of worship, and they were talking about demons all around them."
Shana S. Decree, 45, and her 19-year-old daughter, Dominique K. Decree, are charged in Bucks County with the murder of their loved ones, including three children, in their apartment in Morrisville, Pennsylvania, north of Philadelphia.
The victims were Shana Decree's two other children, Naa 'lrah Smith, 25, and Damon, 13, her sister, Jamilla Campbell, 42, and her twin 9-year-old twins, Imani and Erika. Allen, the authorities said. The seven lived together in the same apartment.
The Shana decree told investigators that the whole family "wanted to die," according to an affidavit of probable cause. However, the authorities indicated that they "did not understand better" the motive or sequencing of the events that led to the killings.
The two women were charged with five homicide counts and one conspiracy charge, the Bucks County Attorney's Office said.
Weeks of concern
"This has been going on for a month," said Sr. Decree to WTVD. "I mean we call children's services, call the police."
A social worker was on a surprise visit Monday when the family was found, according to the affidavit. As no one opened the door, the social worker asked the building maintenance team to check the apartment. Less than 20 minutes later, a housekeeper called 911. The apartment was a mess and the five bodies were found in a bedroom, the affidavit says. Shana and Dominique Decree were found "disoriented" and taken to a hospital, the document says.
According to the affidavit, a social worker from the Bucks County Children's and Children's Social Services Agency had already been to the family's apartment at least once.
"We called and checked everything we had to do," the Sr. decree told WTVD. "Whenever they went there, at least from my point of view, they said the kids were safe and we could not do anything."
Mother and daughter admit to being killed
At first, Shana and Dominique Decree told the investigators that three men had committed the killings, according to the affidavit.
But their story changed and later, the two women declared that they had, along with Shana's sister, Campbell, killed members of their family.
"Shana said everyone, including the children, was talking about suicide," says the affidavit.
In separate interviews with the police, the women claimed to have strangled others to death, according to the affidavit. Dominique Decree's neck had visible injuries, police said.
The cause and manner of death of the victims will not be known until several weeks, the coroner awaiting the results of toxicology, announced the authorities.
The decree Sr. is now mourning the loss of his son, apparently in the hands of his wife and daughter.
"I do not want them in an insane asylum," he told WTVD. "I want to see them in jail for the rest of their lives."
Speaking to reporters Tuesday, Matthew Weintraub, Bucks County Attorney, said that Shana and Dominic Decree would be "sentenced to pay for their crimes".
"We will do our best to ensure justice for these girls and the other three victims," he said.
It was not clear right away if the decrees had been named lawyers.
Nicole Chavez from CNN contributed to this report.