'They killed with apparent impunity, effortlessly dodging capture by the world’s deadliest special forces. Nothing, it seemed, could stop Al Qaeda’s two top Iraqi terrorists as they orchestrated a campaign of high-profile kidnappings, car bombings and executions in Baghdad and beyond. At the height of their reign, one of them, Maher Ahmed Mahmoud az-Zubeidi, better known by his alias Abu Rami, was believed to have been responsible for the murders of 200 people each month. Yet perhaps even more ferocious was his charismatic co-leader, Abu Uthman, whose exploits in two battles in Fallujah earned him the nickname Abu Nimr –...