Six people—five men and a woman—approached a whitewashed house in the postcard-pretty village of Jenins in eastern Switzerland. Glancing cautiously up and down the narrow, darkened street, two members of the team walked to the door while the others hung back. They knew that no one was home. The owner was a few miles away, just across the border in Liechtenstein. One of the men pulled out a leather pouch and extracted a slender piece of metal. He slipped the metal into the lock and gently wiggled it deeper into the mechanism. As he twisted the pick, the slight torque turned against the...