Luigi Mangione's arrest in the UnitedHealthcare CEO murder captivates the nation, but new Dateline reporting reveals who Brian Thompson actually was. Meanwhile, a Cleveland divorce attorney stands trial 13 years after his client's brutal stabbing, and ankle monitors fail to stop two murder suspects in Texas—experts explain why. Investigators solved the Mangione case by working backward through security footage across Manhattan, identifying him through his unmasked face at a hostel rather than tracking his escape route.