"Theory? I don’t even have a hypothesis. You’re the expert; what do you think?"

"You told the Polizei they were Americans," Lau said. "Is that an inference, or can you support it?" Another Anthro 101 question, Gideon thought.

"I told them one of them-the one that spoke-was an American. I could tell from the way he talked."

"What makes you so sure? People speak more than one language."

Gideon sipped his coffee and shook his head emphatically. "Uh uh. I’m not talking about languages; I’m talking about speech patterns. He was born in the U.S., or maybe he came here-I mean there-when he was a kid; five, six, no older."

Lau looked doubtful, and Gideon went on. "I’m telling you, the guy spoke native American; midwestern, maybe Iowa or Nebraska. It’s a question of stress, of lilt."

Lau regarded him blankly. Gideon searched his mind for a simple example.

"Do you remember," he said, "when he said to me, uh…’Try to move and I kill you now’? Well, aside from having no trace of foreign pronunciation, he said it the way only an American would. First, there was the rise-and-fall inflection; unmistakable in simple declarative sentences. Medium pitch at the beginning, up on the ‘kill you,’ and then down on the ‘now.’ "

"Are you telling me-?"

"That’s not the critical part. Some foreigners learn to do that consistently. But the way the words are grouped-the flow, the clotting-that’s what tells you for sure. When an American talks, he jams a lot of words into irregular groupings, so the beat’s uneven. If you know how to listen for it, you can’t miss it."

Lau’s expression was anything but convinced. Gideon continued, his teaching instincts warming to the challenge.

"Let’s say that he’d used a slightly shorter sentence like

’Move and I kill you now.’ In that case he would have given about the same amount of time to ‘move’ and ‘kill you.’ Americans and Europeans both do that. But he threw in that ‘try to’ at the beginning, so that there were a few more words supporting ‘move.’ Well, a native midwestern speaker of what’s sometimes called ‘General American’ tries to compress all three words into the same amount of time as the one word, and then lags a little in the next word group."