LOS ANGELES (CBSLA.com) — A woman and her boyfriend were charged Thursday with the murder of her stepsister, who was found dead last month in northern Los Angeles County.

Britney Sue Humphrey, 22, and Joshua Aaron Robertson, 27, are charged in the death of a 26-year-old Kimberly Harvill of Fresno and were previously charged with kidnapping her three young children.

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Harvill’s body was found Aug. 14 in some brush by a motorist traveling along Gorman Post Road, north of State Route 138. She had been shot in the upper body, according to the Los Angeles County Sheriff’s Department.

Humphrey and Robertson were arrested Aug. 25 in Pueblo, Colo., one day after Harvill’s three young children – ages 2, 3 and 5 – were found safe in a motel outside Albuquerque in the care of a good Samaritan who notified local law enforcement.

The newly amended criminal complaint alleges that Robertson shot Harvill with a handgun. He also faces a felony count of possession of a firearm by a felon with two priors.

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Robertson is scheduled to be arraigned Friday in a downtown Los Angeles courtroom. Humphrey has not yet been sent to Los Angeles County from Colorado.

The criminal complaint alleges Robertson was convicted in Fresno County in 2014 of being a felon in possession of a firearm and evading a pursuing peace officer. He was on post-release community supervision, according to the Los Angeles County Sheriff’s Department.

If convicted, the two could each face up to life in state prison, according to the District Attorney’s Office.

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