DOYLESTOWN (AP) — Attorneys for a man charged in the rape and killing of a 14-year-old girl say they will argue that the child’s adoptive mother masterminded the Pennsylvania slaying.

The (Allentown) Morning Call reports that senior public defender Jack Fagan told a Bucks County judge on Wednesday that 46-year-old Sara Packer’s relationship with murdered teen Grace Packer was “contentious at best.”

Prosecutors have alleged that the child’s mother watched 44-year-old Jacob Sullivan act out a rape-murder fantasy that killed the girl in July 2016. They allege that the couple stored the girl’s body in cat litter for months, then dumped it in a remote area where hunters found it.

Prosecutors have said they plan to seek the death penalty against Sullivan and possibly Packer as well. Sullivan is contesting an earlier confession.