Overview: Angel of Death - Serial killer nurse Charles Cullen confessed to as many as 40 murders, but some believe he killed many, many more patients over a 16-year career. The serial killer speaks to Steve Kroft in his first television interview. Graham Messick is the producer. Watch a preview Rosie's Run for the Roses - One of the hottest American jockeys, Rosie Napravnik, is the only female riding in the upcoming Kentucky Derby and one of only a handful of successful female jockeys in the sport's history. Bob Simon reports. Tom Anderson and Michelle St. John are the producers