Recently, we told you of a Pennsylvanian woman who had been charged with murder after the remains of her adopted daughter, who disappeared over the summer, were discovered in the woods. This already disturbing tale has gotten much sicker, as prosecutors bring forth an appalling motive.

Sara Packer told police that her daughter, 14-year-old Grace Packer, disappeared on July 8 after the two got in an argument over whether or not Grace was allowed to visit a friend. Packer told authorities Grace disappeared along with $300 in cash, insinuating that perhaps she’d run away. Then, pieces of Grace’s body was discovered by hikers in a remote area of the woods on Halloween. Police, already suspicious of Packer given her disinterest in the search for her supposedly missing daughter, arrested Packer and charged her with murder earlier this month.

Grace Packer (Image: Family Photo)

Now, Bucks County D.A. Matthew Weintraub says that Packer and her boyfriend, Jacob Sullivan, together killed the teen, and that her final days were “probably the most horrible and traumatic that any person should ever have had to experience.”

Authorities allege that the couple forced Grace into the attic of their rented home, and that Packer watched as Sullivan beat and raped the teen. Then, Grace was tied up, gagged, poisoned and abandoned. Later, when the poison had failed to do its work, Sullivan strangled Grace.

Jacob Sullivan (Image: CBS3)

The couple then allegedly tried to mask the small of the decomposing body with cat litter, but decided to dismember and dump the body after police stopped by to check up on the missing persons case. The couple tried to kill themselves via an overdose, but failed. On December 30, Sullivan began to tell employees at the hospital where they received treatment what he had done.

Grace’s biological mother lost custody of Grace and Grace’s little brother in 2004. Sara Packer and her then-husband, David Packer, adopted both children. In 2011, David Packer pleaded guilty to sexually assaulting a child. The Packers divorced, and Sara Packer retained custody of both siblings.