Ferguson Police Chief Thomas Jackson released several police reports and documents during a news conference where he also identified the officer involved as Darren Wilson, who has been on administrative leave since he shot 18-year-old Michael Brown on Aug. 9.
Police previously refused identifying the officer, citing concerns over the officer's safety.
Brown and his friend, Dorian Johnson, were suspected of taking the cigars from a convenience store in Ferguson that morning, according to police reports. Jackson said Wilson went to the area after a call to police reporting a "strong-arm" robbery just before noon. He said a dispatcher gave a description of the suspect, and that Wilson encountered Brown a few minutes before another officer arrived.
Jackson said Wilson is a six-year veteran of the police department, but he refused to release any other details about the officer.
Wilson wastreated for injuries after the incident, said Jackson, who told CBS affiliate KMOV that the officer "was hit" and the "side of his face was swollen."
The family's attorney, Benjamin Crump, accused police of trying to draw attention away from Brown's death. He said Brown's parents were "incensed" by what he calls "the old game of smoke and mirrors."
"It's bad enough they assassinated him, and now they're trying to assassinate his character," Crump said.
Johnson acknowledged to the FBI and other investigators that he and Brown went to the store and "that he did take cigarillos," his attorney, Freeman Bosley, told MSNBC.
Bosley said he was aware of security video from the store but had not seen it.
Police released security video, dated Aug. 9, that appears to show a man wearing a ball cap, shorts and white T-shirt grabbing a much shorter man by his shirt near the store's door. A police report alleges that Brown grabbed a man who had come from behind the store counter by his shirt and "forcefully pushed him back" into a display rack.
Brown's uncle, Bernard Ewing, questioned whether Wilson really believed Brown was a suspect. He noted Johnson's account that the officer told the two young men to get out of the street and onto the sidewalk, and that Brown had his hands up when he was shot.
"If he's a robbery suspect, they would have had the lights on," Ewing said. "If you rob somebody, you would tell them, 'Get on the ground' or something, not, 'Get off the sidewalk.'"
"It still doesn't justify shooting him when he puts his hands up," he added. "You still don't shoot him in the face."
Brown's death has sparked several days of clashes with furious protesters in the city. The mood was quelled on Thursday after the governor turned oversight of the protests over to the state Highway Patrol. State troopers walking side-by-side with thousands of peaceful protesters replaced the image of previous nights: police in riot gear and armored tanks.
But the police chief's announcement Friday was met with immediate disbelief and anger by several dozen community members who also attended the news conference, which was hastily held at a gas station burned during a night of looting earlier in the week in Ferguson, a town of 21,000 that is nearly 70 percent black and patrolled by a nearly all-white police force.
"He stopped the wrong one, bottom line," yelled Tatinisha Wheeler, a nurse's aide who was at the news conference.
A couple dozen protesters began marching, chanting "Hands up, don't shoot" and "What do we want? Justice! When do we want it? Now!"
Gov. Jay Nixon urged the community to be patient, saying the investigation into the fatal shooting needs to be completed before drawing conclusions.
"Nothing should deter figuring out how and why Michael Brown was killed," Nixon said at a press conference.
Police have said Brown was shot after an officer encountered him and another man on the street during a routine patrol. They say one of the men pushed the officer into his squad car, then physically assaulted him in the vehicle and struggled with the officer over the officer's weapon. At least one shot was fired inside the car before the struggle spilled onto the street, where Brown was shot multiple times, according to police.
Dorian Johnson has told media a different story. He said an officer ordered him and Brown onto the sidewalk, then grabbed his friend's neck and tried to pull him into the car before brandishing his weapon and firing. He said Brown started to run and the officer pursued him, firing multiple times.
Tensions in Ferguson boiled over after a candlelight vigil Sunday night, as looters smashed and burned businesses in the neighborhood, where police have repeatedly fired tear gas and smoke bombs.
By Thursday, there was a dramatic shift in the atmosphere after the governor assigned protest oversight to Highway Patrol Capt. Ron Johnson, who is black and grew up near Ferguson. He marched alongside protesters.
"We're here to serve and protect," Johnson said. "We're not here to instill fear."
The streets were filled with music, free food and even laughter. When darkness fell - the point at which previous protests have grown tense - no uniformed officers were in sight outside the burned-out QuikTrip convenience store, which had become a flashpoint for standoffs between police and protesters.
"All they did was look at us and shoot tear gas," Pedro Smith, who has participated in the nightly protests, said Thursday. "This is totally different. Now we're being treated with respect."
The more tolerant response came as President Barack Obama spoke publicly for the first time about the shooting - and the subsequent violence. Obama said there was "no excuse" for violence either against the police or by officers against peaceful protesters.
Attorney General Eric Holder has said federal investigators have interviewed witnesses to the shooting.
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