Sebastian Rotella is a senior investigative reporter at ProPublica.org. He is the author of "Twilight on the Line: Underworlds and Politics at the U.S.-Mexico Border."
Privately, some officials express suspicion that U.S. agencies tracked Headley’s movements and picked up bits and pieces about the plot without realizing he was deeply involved.
Officials say the terror threat against the U.S. may be widening to include an organization with thousands of hardened fighters who have not previously struck in the West.
The Border Patrol and Mexican police are training together and sharing intelligence for the first time. The goal: a joint attack on cross-border flows of drugs, guns, and migrants.