Dateline: Secrets Uncovered (2017)

S16E8 A Deal With the Devil

Operating as a shadow asset for the FBI, a confidential informant secretly moonlights as a serial killer, methodically claiming victims while feeding the Bureau just enough intel to stay indispensable. As the body count climbs, federal agents unknowingly shield their prized source, never suspecting that the monster they hunt is the very man they trust—until a critical oversight forces a reckoning between justice and complicity.