Mother and son plead not guilty in Pennsylvania soccer player's stabbing death

A mother and son charged in the stabbing death of an 18-year-old college soccer player in Washington County, Pennsylvania, pleaded not guilty on Tuesday. 

Royce Moser, 18, is accused of killing his girlfriend, Karoline Heintz, at his father's home in North Strabane Township on Aug. 19. Investigators said his mother, Rachel Moser, 56, helped him cover up the crime. The two appeared in court for a formal arraignment on Tuesday. 

Pennsylvania State Police said Royce Moser and Heintz, a soccer player at PennWest University who was starting her freshman year, were having a discussion about the future of their relationship outside of his father's house when it went "a little bit south."

Police said Royce Moser went into the home, grabbed a knife from the kitchen and stabbed Heintz in the chest. He later told investigators that he had a "demon take over," according to court paperwork. Heintz fell out of her vehicle, and police said Royce Moser picked her up, put her in the hatch of her Jeep Cherokee and drove her to his mom's house in Beallsville. 

Troopers said Royce Moser talked to Rachel Moser about what to do, and she told him to get changed while she put the knife in a garbage bag, washed his clothes and tried to clean the Jeep. 

Investigators said Royce Moser then drove the Jeep to a parking lot near the California Public Library, with his mom following him in another vehicle. They left the Jeep and drove back to Rachel Moser's home in Beallsville together, police said. 

Authorities said Heintz was found dead inside the back hatch of the Jeep after her family couldn't reach her and called 911.