Manhunt—Boston Bombers

At 2:50 pm on April 15, 2013, two bomb blasts turned the Boston Marathon finish line from a scene of triumph to tragedy, leaving three dead, hundreds injured, and a city gripped by heartbreak and terror. Less than five days later, the key suspects were identified and apprehended with one dead, the other in custody. How did investigators transform the chaos of the bombing into a coherent trail?