MINISERIES PREMIERE: This documentary miniseries, a compilation of case studies about recent mass shootings in the U.S., begins with what may be the most depressing opening credits sequence ever presented. Each week, this series will recount and analyze a different case, utilizing 911 recordings, eyewitness accounts, security footage, and interviews with survivors, relatives, first responders and medical personnel. Tonight’s opener is devoted to the 2012 mass shooting at the suburban Color