After a police killing, it can be hard to get a clear picture of what exactly happened. Like the case of Mario Woods, who was shot and killed by San Francisco police in 2015. Nearly three years later, as the civil case is being prepared for trial, we're getting new information in court filings -- including new testimony from the man Woods stabbed a couple hours before he was shot and a new video of the shooting taken from a different perspective. Guest: Alex Emslie, KQED criminal justice reporter