Spc. Caleb Barnes, a member of 741st Military Intelligence Battalion based at Fort Meade, Maryland, is charged in Lehigh County with criminal homicide, abuse of a corpse and statutory sexual assault.
The 14-year-old stands accused of helping Barnes bury the body of her 54-year-old mother, The (Allentown) Morning Call reported. The girl, who was not not named by the newspaper, was sent to a juvenile detention facility, according to The Morning Call.
The relationship had gone on since October, Lehigh County District Attorney Jim Martin told The Morning Call, and the mother had found out and attempted to have the teenager break it off.
Authorities said police found a parked vehicle with a large pool of blood inside about 4:15 a.m. Monday. Police said the car later disappeared, but officers noticed that dirt had been disturbed and found the 54-year-old's body buried.
Police traced the car to her home, where they questioned Barnes, the girl and a man the Morning Call identified as the girl's father, whom the paper said was sleeping and wasn't aware of the alleged relationship between Barnes and his daughter.
Barnes' attorney, public defender Richard Webster, didn't immediately return a call to The Associated Press seeking comment.
Barnes joined the military in 2012, according to personnel information provided by an Army spokesman. He graduated advanced training from the Presidio of Monterey, California, in September. His awards include the Good Conduct Medal and National Defense Service Medal.