A white police officer in the San Francisco Bay Area shot and killed a black man in the middle of a busy intersection about a minute after trying to stop him on suspicion of throwing rocks at cars last month, newly released video shows.Graphic body camera footage showing Officer Andrew Hall shooting Tyrell Wilson, 33, within seconds of asking him to drop a knife was released on Wednesday, the same day prosecutors charged Hall with manslaughter and assault in the fatal shooting of an unarmed Filipino man more than two years ago.