A profile of Moktar Belmoktar, Al-Qaida’s “most difficult employee,” who was responsible for a major attack on an Algerian BP plant and, according to U.S. and Libyan forces, was killed in an air strike on Sunday.

While fleeing their Mali stronghold, al-Qaida left behind documents describing not how to terrorize a population, but how to govern.

An investigation into the ill-fated text messaging platform ZunZuneo.

What the CIA really knew about Robert Levinson, a retired FBI agent who disappeared in 2007.

An 88-year-old woman is taken from her Wisconsin farmhouse. Inside the investigation to find her.

Israel Keyes confessed to multiple murders, but committed suicide before revealing all the details.