CARROLLTON, Ga. (CBS News) — A university instructor in Carrollton has been charged with killing an 18-year-old student who was shot while sitting in a car.

In a news release, the Carrollton Police Department said that Richard Sigman, 47, is charged with murder and aggravated assault in the shooting death of Anna Jones, 18. Police said they believe Jones was killed when Sigman shot into a parked car following an argument with a man at a pizza restaurant. The shooting happened shortly after midnight Saturday.

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Police said a man told security that Sigman had threatened to shoot him during an argument, and security then asked Sigman to leave. Investigators believe when Sigman left, he walked to the parking deck and started shooting into a parked vehicle, hitting Jones. Friends drove Jones to a hospital, where she was pronounced dead, police said.

It wasn’t immediately clear if Sigman has a lawyer to speak on his behalf.

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The University of West Georgia told CBS News in a statement that Sigman’s employment has been terminated. A current course catalog listed Sigman as a lecturer in business administration.

The school said it “continues to work with the city of Carrollton Police Department, which leads this ongoing investigation.”

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