Karlie Hall, in a Facebook photo.

Karlie Hall, a 2014 graduate of Unionville High School, was found in her room at the Lancaster County university at about 5:20 a.m. Sunday. Gregorio Orrostieta, 19, of Kennett Square, was initially charged with aggravated assault, but the charges were changed to criminal homicide after an autopsy revealed that Hall suffered trauma and strangulation wounds.  He is being held without bail.

. He is a 2014 graduate of Kennett High School but is not a student at Millersville.

According to a police affidavit, first responders on the scene found Orrostieta "kneeling over Hall and attempting to administer CPR."

Orrostieta told investigators that he and Hall had argued at a party, and that Hall had hit him. He said the couple made up and returned to Hall's dorm room at around 1:30 a.m. He said that they argued again, and he admitted to shoving Hall, knocking her down and causing her to hit her head on a chair. He also said he "gave Hall a 'back hand' to her face, at which time the altercation ceased when Hall became unresponsive," according to the affidavit.