"An off-duty police officer shot and killed a black teenager in St. Louis on Wednesday night, setting off a demonstration just days ahead of long-scheduled protests in Missouri about the use of lethal force by the authorities. The St. Louis police chief, D. Samuel Dotson III, said at a news conference that the teenager had fired at least three shots toward the officer, a six-year veteran who was working in the city’s Shaw neighborhood for a private security firm. Chief Dotson said that the officer had fired 17 rounds, but that he did not know how many times the teenager had been hit. The teenager’s family disputed the police account, and a woman who said she was his cousin told The St. Louis Post-Dispatch that he had been unarmed. “He had a sandwich in his hand, and they thought it was a gun,” the cousin, Teyonna Myers, told the newspaper. “It’s like Michael Brown all over again.” here we go again.