(FERGUSON, Mo.) -- The Ferguson, Missouri police officer who shot and killed an unarmed teenager suffered "a serious facial injury" in the altercation before firing the fatal shots, according to a source close to the officer who spoke to ABC News Wednesday.
The characterization about Officer Darren Wilson being injured in his confrontation with Michael Brown emerged on the day that a grand jury was expected to begin hearing evidence in the shooting.
Brown, 18, was shot and killed by Wilson on Aug. 9, and protesters have been angrily calling for Wilson's arrest and indictment since that day.
St. Louis County Prosecutor Robert McCulloch cautioned on Wednesday that a decision on whether or not the officer would be indicted will not come quickly. He told ABC News "our target date is the middle of October" for wrapping up the evidence and asking the jury to decide whether to charge Wilson. Grand juries typically meet one day a week.
A source close to Wilson told ABC News that during the struggle at the patrol car, Wilson suffered "a serious facial injury."
The injury was not described, but last week Ferguson Police Chief Tom Jackson said that Wilson had swelling to the side of his face.
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