Dashboard video shows a police officer making a routine traffic stop. Cellphone video shows the officer shooting the fleeing motorist in the back. What remains a mystery is what happened during the minutes in between that led the police officer to become a killer. The dash cam footage released by state police on Thursday showed North Charleston Officer Michael Thomas Slager pulling over black motorist Walter Scott for a broken brake light last weekend. Slager, who is white, has been charged with murder in Scott’s death. […] What’s missing is what happens from the time the two men run out...