The police slayings of two black men after traffic stops are the focus of murder trials unfolding in two cities. They also are among a series of cases across the country that have raised a national debate over race and policing.

Former University of Cincinnati officer Ray Tensing is on trial in the 2015 fatal shooting of 43-year-old Sam DuBose. Former North Charleston, South Carolina, officer Michael Slager is on trial in the April 2015 shooting of 50-year-old Walter Scott. Both former officers are white.

Other cases of the deaths of blacks after police encounters range from the fatal shooting of a 12-year-old boy in a Cleveland recreation area in November 2014 to that of a 66-year-old woman in her Bronx, New York, apartment last month.