The jumbled picture emerging of Orlando shooter Omar Mateen — his statements to friends and coworkers and his tangled personal history — lay bare the dilemma for law enforcement in confronting the growing threat of home-grown lone wolf terrorists. “The key challenge is to figure out, when does an individual move from being aspirational to operational?” says Fran Townsend, former Homeland Security Advisor and counter-terrorism expert in the George W. Bush White House.