This is the story of well, I can't tell you his name, because, as he told me with a nervous laugh, "I'm still a scared man inside, Bob."

Call him Ahmed. He is a citizen of Britain, where he completed his medical residency, but he was born in Pakistan. For the past several years, he has been a faculty member at a leading U.S. university medical center. His wife and children, also British citizens, live here with him.