Anwar al-Awlaki’s youngest brother, Ammar, was nothing like him. While Anwar embraced a radical interpretation of Islam and preached jihad against the United States, Ammar was pursuing a career at an oil company in Yemen. Ammar was Canadian-educated and politically well connected. He dressed in blue jeans, wore hip Armani eyeglasses and sported a goatee. His hair was slicked back, and he had the latest iPhone. In February 2011, Ammar told me, he was in Vienna on a business trip. He had just returned to his hotel after sampling some of the local cuisine with an Austrian colleague when the phone in his room rang. “Hello, Ammar?” said a man with an American accent. “My wife knows your wife, and I have a gift for her.”

Ammar went down to the lobby and saw a tall, thin white man in a crisp blue suit. They shook hands. “Can we talk a bit?” the man asked, and the two sat down in the lobby. “I don’t actually have a gift for your wife. I came from the States, and I need to talk to you about your brother.” 

“I’m guessing you’re either FBI or CIA,” Ammar said. The man smiled. Ammar asked him for identification.