The adoptive mother accused in the rape and murder of 14-year-old Grace Packer knew that her then-husband had sexual contact with the girl's foster sister, Lehigh County District Attorney James B. Martin said Thursday.

Sara Packer, 41, was aware that David Packer had engaged in sexual activity with Grace's foster sister around 2010, when the girl was 18. Late that year, David Packer was charged with sexually assaulting the girl when she was younger, as well as Grace.

The disclosure by the prosecutor raises the question of whether Sara Packer had previously tolerated or turned a blind eye to sex abuse in her household - and against her adopted daughter Grace. Bucks County prosecutors, who are investigating the homicide, say that after moving to Abington Township, Sara Packer and her boyfriend, Jacob Sullivan, allegedly killed the girl in a "rape-murder fantasy" last summer.

The charges announced last weekend have sparked a slow trickle of information from around the region about the couple, their past, and what might have led to the crime.

Sara Packer had worked as a supervisor of adoptions in the Northampton County Children, Youth and Families division. During her marriage, she and David Packer lived near Allentown, and he was investigated and prosecuted on the sex-assault charges by the Lehigh County District Attorney's Office.

Grace's older foster sister had been assaulted by David Packer in 2007 when she was 15, court records say. She was not Grace's biological sibling, Martin said.

Sara Packer "claimed at the time she didn't know about anything other than the events that occurred after the girl turned 18," the Lehigh County district attorney told the Inquirer on Thursday. "That's bizarre in itself."

Prosecutors had no evidence Sara Packer knew about her husband's abuse of Grace, Martin said.

David Packer ultimately pleaded guilty, was sent to prison, and registered as a Megan's Law offender.

As that case was unfolding in 2010, Sara Packer was terminated from her $45,000-a-year position as an adoptions supervisor, Northampton County Controller Stephen J. Barron Jr. said in an interview Thursday.

Packer had worked in the child welfare office from January 2003 to January 2010, overseeing caseworkers and paperwork associated with pending adoptions headed for Common Pleas Court.

He said Sara Packer had had no criminal record when she was hired by the county but he did not know whether she had come under supervision or reprimand during her employment tenure.

Barron said he contacted Bucks County investigators late last month and urged them to investigate her employment history.

"You need to subpoena her personnel records," Barron said he told a county detective, "because you need to look at that."

After David Packer's arrest, there was a joint investigation by prosecutors and the county Children and Youth department into the family, but Martin did not have information about the outcome.

Barron said officials in the Lehigh Valley should be forthcoming with what they knew about the girl's mother, and whether they had done enough to keep the child safe after her adoptive father was prosecuted seven years ago.

"It seems that the system failed in protecting her," Barron said.

David and Sara Packer had been separated, but were not legally divorced, according to public records, until August 2016 - the month after Grace was killed.

The criminal complaint alleges that Sullivan raped Grace in July, after which he and Packer drugged her and left her to die in their attic. When they found her alive the next day, Sullivan allegedly strangled her.

The couple kept her body in an attic for four months, until they got nervous about police questioning, dismembered her body, and dumped her remains in Luzerne County. Her body parts were found by hunters on Oct. 31.

Sullivan and Packer were arrested in the homicide on Jan. 8. They are awaiting a Jan. 20 preliminary hearing in Bucks County.