FERGUSON, Mo. — Michael Brown let his 16th birthday come and go without bothering to apply for a driver’s license. There was no need, his family said. He preferred to walk.

In Ferguson, where Mr. Brown was living with his grandmother, he walked nearly everywhere: on Canfield Drive, where his grandmother kept a small apartment, and several blocks away on the bustling commercial strip of West Florissant Avenue, a four-lane road full of hair salons and cheap restaurants that is the de facto downtown of the neighborhood.

It was during one of Mr. Brown’s walks down Canfield Drive one week ago when he would have an unlikely collision. It involved Mr. Brown, a black teenager who seemed to have avoided most of the traps that dragged down many of his peers, and a white police officer, Darren Wilson, with an admirable record. When it was over, Mr. Brown was dead and Officer Wilson was facing an uncertain legal and professional future.

Chief Thomas Jackson of the Ferguson Police Department, at a hastily called news conference on Friday morning, revealed Officer Wilson’s name for the first time. He has been a police officer for about five years, but Chief Jackson offered scant information about his life and work.