LOS ANGELES (CBSLA.com) — Two people, including the stepsister of a woman whose body was found in northern Los Angeles County this summer, will be arraigned Monday in connection with the woman’s killing.

According to the Los Angeles County District Attorney’s Office, Britney Sue Humphrey, 22, and her boyfriend, Joshua Aaron Robertson, 27, have been charged with killing Humphrey’s 26-year-old stepsister, Kimberly Harvill, of Fresno, on or about Aug. 14.

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The criminal complaint alleges that Robertson personally and intentionally discharged a handgun, killing Harvill. Harvill’s body was found in brush by a motorist traveling along Gorman Post Road.

She had been shot in the upper body, according to the sheriff’s department.

Humphrey and Robertson were arrested Aug. 25 in Pueblo, Colorado, just one day after Harvill’s three young children were found safe in a motel outside Albuquerque, New Mexico, in the care of a good Samaritan who notified local law enforcement.

At the time of their arrests, the two were charged with three counts of kidnapping involving the children, and were wanted for the questioning in connection with Harvill’s killing.

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A murder charge was added in September.

Robertson has also been charged with a felony count of possession of a firearm by a felon with two priors.

The criminal complaint alleges that Robertson was convicted in Fresno County in 2014 of being a felon in possession of a firearm and evading a pursuing peace officer.

Robertson was on post-release community supervision, according to sheriff’s deputies.

If convicted as charged, the pair could each face up to life in state prison.

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