The police shooting of Paul Childs, a 15-year-old with developmental disabilities, rocked the Denver community in 2003. The killing led to the creation of an independent monitor, a watchdog over the city's police and sheriff's departments. Nick Mitchell was only the second person to step into that role in Denver. He spent 8 years working with communities and law enforcement. And he's moving on, just as the DPD reckons with how it handled last summer's Black Lives Matter protests.