FERGUSON, Mo. (ABC News) - The Ferguson 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 today.
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 David McCullough cautioned 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.
The news came Wednesday as protesters and police faced off again in Ferguson overnight, with a thrown water bottle briefly re-igniting the turmoil, but authorities are hopeful the unrest in the St. Louis suburb is reaching a turning point.
Missouri Highway Patrol Capt. Ron Johnson, speaking at an early-morning news conference, thanked volunteers, clergy and community activists for helping to quell the discontent that has lingered since the Aug. 9 police shooting of unarmed teen Michael Brown.
"They had a calming influence on the younger people," Johnson said. "Tonight, we saw a different dynamic."
Authorities arrested 47 people overnight, including one person for the third time, Johnson said. Some of those arrested had made threats to kill a police officer, Johnson said, but the clashes didn't feature some of the heightened measures of previous nights. No Molotov cocktails or shootings from protesters, no smoke bombs or tear gas from police.
Attorney General Eric Holder also traveled to Ferguson Wednesday to meet with FBI and other officials carrying out an independent federal investigation into Brown's death.
Holder addressed the situation in an editorial for the St. Louis Post-Dispatch newspaper.
"Our investigation into this matter will be full, it will be fair, and it will be independent," Holder wrote. "And beyond the investigation itself, we will work with the police, civil rights leaders, and members of the public to ensure that this tragedy can give rise to new understanding and robust action aimed at bridging persistent gaps between law enforcement officials and the communities we serve."