ALLENTOWN, Pa. (WJZ) — A Maryland soldier is behind bars, charged with killing his girlfriend’s mother. It happened after she apparently tried to break off his relationship with her 14-year-old daughter.

Jessica Kartalija has the story.

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Caleb Barnes, 20, is accused of killing Cheryl Silvonek.

“They purchased various materials, including alcohol, bleach, bleach wipes,” said James Martin, Lehigh Valley D.A.

Barnes, on a weekend leave from Fort Meade, and his 14-year-old girlfriend are accused of stabbing Silvonec several times in her car, parked right outside her home in Lehigh County, Pennsylvania, then burying her body in a shallow grave and hiding her car.

A neighbor noticed something suspicious.

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“There was blood splattered across the dash and dripped on the dash. It was horrifying,” one man said.

“There was what I would describe as a large quantity of blood on the interior of the vehicle,” said Martin.

Police found the couple in an upstairs bedroom of the family’s home. The girl’s father was still asleep inside.

As for a motive:

“The mother became aware of the relationship and was attempting to have her daughter break it off,” said Martin.

Barnes is charged with homicide, abuse of a corpse and statutory sexual assault.

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The girl is charged with abuse of a corpse and tampering with evidence. She could be charged as an adult in the case.