FERGUSON, Mo. — Michael Brown, the unarmed black teenager who was killed by a police officer, sparking protests around the nation, was shot at least six times, including twice in the head, a preliminary private autopsy performed on Sunday found. One of the bullets entered the top of Mr. Brown’s skull, suggesting his head was bent forward when it struck him and caused a fatal injury, according to Dr. Michael M. Baden, the former chief medical examiner for the City of New York, who flew to Missouri on Sunday at the family’s request to conduct the separate autopsy. It was...