BUCKS COUNTY, Pa. (KYW Newsradio) — It was supposed to be the start of jury selection, but it turned out to be a guilty plea for a 46-year-old accused of killing a teenage foster child in what was described as a "rape-murder fantasy."

Jacob Sullivan has pleaded guilty to rape, kidnapping and first-degree murder, admitting to the facts which took much longer than usual to read into the record.

This case started on July 11 with a missing persons report in Abington as Sullivan’s girlfriend and co-defendant Sara Packer, the victim’s foster mother, reported 14-year-old Grace Packer missing. BREAKING: Jacob Sullivan admits to killing and raping 14-year-old Grace Packer. Also learned his co-conspirator, Sara Packer has been cooperating and plans to plead guilty at the appropriate time. @KYWNewsradio pic.twitter.com/iI9Cy5SPVl — Jim Melwert (@JMelwert) — Jim Melwert (@JMelwert) February 19, 2019 RELATED: Jury selection starts in case prosecutors call 'rape-murder fantasy'

The investigation began when Sara Packer reported her daughter missing in Abington, but then didn’t drop off pictures of the girl, or even tell police she was moving to Quakertown. She also never notified the new school district her daughter was to enroll in.

Sullivan admitted in court that they planned to murder Grace for months.

Sullivan said three days before reporting her missing in July 2016, they drove the girl to Quakertown and punched her in the face repeatedly in the attic of a house there. He took Viagra before sexually assaulting her, while her foster mother watched. They forced her to take pills, tied her up and gagged her, and left her to die in the hot attic.

When they found her alive the next morning, Sullivan choked her to death.

They stored the body in a bin filled with cat litter for weeks, before dumping it in Luzerne County.

Sullivan and Packer entered into a suicide pact, but both survived an intentional overdose.

It was revealed at this hearing that 44-year-old Sara Packer has been cooperating with authorities and plans to plead guilty at the appropriate time, avoiding the death penalty.

She is also expected to testify at Sullivan’s penalty-phase hearing, when a jury will decide if he should get life in prison or the death penalty.

Sullivan is expected to return to court Wednesday morning to finish his guilty plea. Before it was finalized, he had to be taken to the hospital due do a spike in blood pressure.