The death of an 18-year-old Millersville University student from Chadds Ford on Sunday, Feb. 8, has been ruled a homicide, Lancaster County authorities said; her boyfriend is in custody.

Following an autopsy on Monday, Feb. 9, for Karlie Hall, a 2014 Unionville High graduate, Dr. Wayne Ross concluded that she died "as the result of strangulation and multiple traumatic injuries," the Lancaster County District Attorney’s Office said.

Prosecutors had already filed aggravated assault charges against Gregorio Orrostieta, 19, of Kennett Square, Hall’s boyfriend, after interviewing him on Sunday. Lancaster County District Attorney Craig Stedman added a criminal homicide charge against Orrostieta on Monday, Feb. 9. “He’s responsible, and we’re going to hold him responsible,” Stedman said.

Members of the Millersville University and Millersville Borough police responded to a call at Bard Hall on the Millersville University campus at approximately 5 a.m. on Sunday, Feb. 8 for a cardiac arrest, a statement from the Lancaster County District Attorney’s Office said.

Upon arrival, officers found an unresponsive, female student in her dorm room, and in conjunction with the Lancaster County Forensics Team and Lancaster County District Attorney’s Office, began an investigation into her death, which was deemed suspicious.

According to the criminal complaint, officers at the scene also found Orrostieta, who had blood smeared on his face, scratches on his chest, and a ripped shirt, kneeling over Hall attempting to administer CPR. He said he and Hall had a verbal altercation earlier at a party and that Hall had slapped him.

Orrostieta, who was not a Millersville student, told police that he and Hall "made up and then returned to Hall's dorm room around 1:30 a.m." He said another fight occurred, and he admitted shoving Hall hard enough that she was knocked to the ground and hit her head on a chair. Orrostieta also said he give Hall a "back hand" to her face, at which point she became unresponsive, the complaint said.

During the course of the investigation, officers interviewed residents of Bard Hall who stated that they heard a disturbance from Room 217 around 2 a.m., including yelling and the sound of furniture being moved, the complaint said.

A resident assistant attempted to make contact with the occupants of the room at 2:30 a.m., but got no response and heard no more noise until police were called about 5 a.m. Investigators reviewed video surveillance from the dormitory verifying that no one else had entered or exited Room 217 during that time period, the complaint said.

Stedman said Orrostieta made the 9-1--1 call. "I have no idea what he was doing during that 2 1/2 hours," Stedman said.

There is no evidence that anyone else is involved, and law enforcement officers are confident that there is no danger to the campus community, the District Attorney’s Office said. Police are urging anyone who may have information related to this investigation to contact them at 717-871-4357.

Orrostieta has been held at Lancaster County Prison after failing to post bail of $1.5 million on Sunday; bail is not an option for homicide defendants. A preliminary hearing is scheduled for Feb. 19, court records said.

According to online records, Orrostieta graduated in 2014 from Kennett High School, where he played soccer. In May, he was one of 11 students who received the Reach Out to the Community (ROC) Award for mentoring kindergarten students at Mary D. Lang Kindergarten Center.

Janet Kacskos, a Millersville University spokeswoman, said the university's focus right now is helping students deal with their grief, including Hall's twin sister, who also attends Millersville. She said students have been encouraged to avail themselves of the school’s counseling services.

A statement from Millersville University President John Anderson posted on the campus website expressed condolences to her family and friends.

“Our university community has suffered an unfathomable loss, the death of one of our students, Karlie Hall, of Chadds Ford, Pa.,” the statement said.  “I ask that you join me in sending our thoughts and prayers to Karlie’s family and friends.  If you personally knew Karlie, please accept my heartfelt condolences at this most difficult time.”

Unionville High School Principal Paula Massanari said those at UHS who knew Hall were shocked. She said Hall and her twin sister graduated UHS together and both went to Millersville.

"You rarely saw them apart," Massanari said. "I was struck by their friendship. They were virtually inseparable. I wasn't surprised that they both went to Millersville."

Massanari sent a letter to parents on Monday expressing sadness over the death and letting them know that UHS teachers “kept a close watch for anyone who seemed to be upset.” She said she spoke to Hall’s mother and “offered her our deepest sympathy, along with our support in the coming days, weeks and months.”

The principal also encouraged parents to have their children contact a school counselor if they had been impacted by Hall’s death.

On Facebook, an outpouring of messages expressed shock and sadness over Hall’s death, many referencing her wonderful sense of humor and kind heart.

“RIP, you deserved so much better,” one friend wrote.