MANHEIM, Pa. - A central Pennsylvania man suffocated his 17-year-old girlfriend by sitting on her head after he intentionally drove into a guardrail at about 100 m.p.h. in the middle of the night, authorities said.

Police filed homicide and other charges Friday against Benjamin Daniel Klinger, 19, for the Dec. 4 death of Sammi Heller on an interstate near Manheim. Klinger is accused of crashing on purpose, then killing Heller by sitting on her until she was asphyxiated.

"At first glance, this appeared to be simply another tragic vehicle accident," Lancaster County District Attorney Craig Stedman told the Lancaster Intelligencer Journal-New Era. "However, the police worked hand in hand with our forensic experts and saw this was far more complicated, sinister, and certainly criminal."

A man who answered the telephone at Klinger's Elizabethtown home Thursday said Klinger did not have a lawyer and declined to comment.

Heller, a senior at McCaskey High School, was described in her obituary as athletic and a lover of motorcycles and horses.

She allegedly told a friend that Klinger previously tried to scare her while driving and had threatened to kill them both in a crash. Another witness told detectives that Heller said Klinger would push Heller into walls and once pushed her down a set of stairs, police alleged. Heller may have been pregnant, and police fielded conflicting reports about whether Klinger was the father.

A truck driver who came upon the 2 a.m. crash heard Heller screaming, and was told by 911 operators not to move the crash victims. "Klinger was observed by the officers to be what appeared as 'slipping in and out of consciousness,' because he would close his eyes for several seconds, moan, and then reopen his eyes while continuing to be positioned on top of the victim's head and torso while the victim was face down," police wrote. Based on medical records, investigators later concluded Klinger was feigning being unconscious.