By David DeKok

HARRISBURG, Pa. (Reuters) - Authorities on Tuesday considered whether to charge a 14-year-old Pennsylvania girl as an adult in the stabbing death of her mother, who apparently had tried to break up the girl's romance with a 20-year-old soldier.

The girl's boyfriend, Caleb Barnes, confessed to stabbing Cheryl Silvonek, 54, repeatedly in the neck as her daughter watched while they were seated in the family car at their home in Orefield, Pennsylvania, early on Sunday, according to court records.

Police sought cell phone records and emails between the girl and Barnes, a soldier who was off duty from Fort Meade, Maryland, said the girl's lawyer, John Waldron of Allentown. Authorities sought to determine possible premeditation before deciding whether to charge the girl as an adult or add additional charges, he said.

Barnes and the girl, whose name was not released, were arrested on Sunday after Ray Werley, who lives about 2 miles from the Silvonek house, was awakened by his barking dog at about 4 a.m. Sunday and spotted a car parked outside.

"I just thought it was broken down until I saw the blood," Werley said on Tuesday. "It was smeared over the windows."

He alerted police, who found Silvonek's body buried in a forest about 20 yards from where the car had been parked. Authorities said Silvonek was killed in her own driveway and the couple then drove her body to the spot near Werley's house to dispose of her.

Prosecutors believe Silvonek was trying to break up the romance because of the age of her daughter, who turned 14 last month, said a spokeswoman for Lehigh County District Attorney James Martin.

The girl met Barnes at a concert in October and they began a mostly online relationship, Waldron said. Her father, David Silvonek, a pharmacist, did not know about the romance.

The girl is charged as a juvenile with abuse of corpse, hindering apprehension or prosecution and tampering with evidence.

"She is too young in a lot of ways to know what she was involved in," Waldron said.

Barnes was held without bail after his arraignment on Monday on charges of criminal homicide, abuse of a corpse and statutory sexual assault.

He enlisted in the Army in February 2012 in El Paso, Texas, Fort Meade officials said.

(Editing by Barbara Goldberg and Bill Trott)