MANHEIM, Pa. (AP) — A man suffocated his 17-year-old girlfriend by sitting on her head after he intentionally drove into a guardrail at about 100 miles per hour in the middle of the night, authorities said.

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

"At first glance, this appeared to be simply another tragic vehicle accident," Lancaster County District Attorney Craig Stedman told the Intelligencer Journal/Lancaster 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 home in Elizabethtown, a 20-minute drive from Manheim, said Thursday that Klinger did not have a lawyer and declined to comment further.

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

She told a friend that Klinger previously tried to scare her while driving and that he had threatened to kill them both in a crash, authorities said. A witness told detectives that Heller said that Klinger would push her into walls and once pushed her down a set of stairs, police alleged.

Investigators looked into whether Heller may have been carrying Klinger's unborn child, but the newspaper reported Thursday, citing Stedman, that an autopsy showed she was not pregnant.

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. When police arrived, Klinger was sitting on top of Heller's head and torso, according to the arrest affidavit.

"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.

Story continues

Based on medical records, investigators later concluded Klinger was feigning being unconscious.

Detectives recovered marijuana, cash, a digital scale, a pipe, pills and a black air pistol from the wreckage.

Klinger was also charged with aggravated assault, drug offenses and driving violations.

Separately, he faces a charge of simple assault after being accused of running over Heller's foot in May and two counts of disseminating explicit sexual materials to a minor after being accused of sending out photos and video of Heller.