Karoline Heintz posing with Royce Moser for prom. (Photo: kheintz_57)Karoline Heintz was days away from beginning her first college soccer season, when the 18-year-old was found dead in her jeep near PennWest University in Pennsylvania. Her boyfriend, Royce Moser, later allegedly told his mother that a “demon” had taken over and told him to stab her, according to reports.Pennsylvania State Police charged Moser with criminal homicide. His mother, Rachel Moser, was also charged after investigators alleged that she helped him clean the Jeep and return it to California Borough with Heintz’s body inside.Heintz was found at about 12:24 AM in the rear hatch area of her jeep Cherokee near the California Area Public Library. Her family had contacted authorities after she failed to check in and return to campus housing as expected.Police trace events to relationship discussionEarlier that evening, Heintz had attended a family gathering before meeting Moser at his father’s home in North Strabane Township. The couple sat in her vehicle and discussed their relationship, including how it might continue once she began college.Pennsylvania state trooper Rocco Gagliardi said the conversation deteriorated. Moser allegedly told Heintz he had something for her, went inside the house and returned with a kitchen knife, People magazine reported.He then allegedly stabbed her in the chest. State police said that after Heintz fell from the vehicle, he placed her body in the rear hatch area and drove to his mother’s home in Beallsville, where investigators say he sought her help.Police allege that boyfriend's mother helped clean JeepInvestigators allege that Rachel Moser helped her son clean blood from the Jeep, while efforts were also made to clean his clothes. He later drove the vehicle towards California Borough as his mother followed in another car.The jeep was left near the California Area Public Library with Heintz’s body still inside. Her family helped authorities locate the blood-stained vehicle by tracking her whereabouts, with reports saying an AirTag was used to trace it.Royce and Rachel Moser were arrested Thursday. According to reports, he allegedly told his mother that a “demon” had taken over and told him to stab Heintz. State police did not disclose a motive and did not say whether he had a mental-health history.Royce and Rachel Moser face chargesRoyce Moser has been charged with criminal homicide, tampering with evidence, abuse of a corpse and obstruction. His mother faces charges including tampering with evidence, obstruction, hindering the apprehension of a fugitive and abuse of a corpse.As Rachel Moser was taken to a police vehicle after her arrest, she apologised to Heintz’s family. “I’m sorry,” she said. “That my son took a life.”Heintz was set to begin college soccer seasonHeintz completed high school at Peters Township in June and was due to begin her first year at PennWest University’s California campus. She was listed as a freshman defender on the women’s soccer roster and had committed to play NCAA Division II soccer.PennWest University said it was “deeply saddened” by her death and offered condolences to her family, friends and others affected. The university said the incident occurred off campus and that its police department was cooperating with Pennsylvania State Police in the investigation.