Cities can defend against human trafficking — they just need to know what to look for 

USA TODAY - For more and to sign up click here Carol Merna, opinion contributor Crystal was newly 21. Her life was about to change forever. Her situation was unremarkable — what you might expect in America’s heartland. Awkward, insecure and lonely, she met a man online who said she was beautiful and smart. He was attentive, messaging her frequently and filling her need for companionship. Crystal was smitten. Her…