Every person coming into an investigator's interview is already fearful, says Nate Gordon, director and founder of The Academy for Scientific Investigative Training in Philadelphia. When an interviewer presents himself professionally and behaves in a calm, authoritative manner, a questioning session separates the innocent from the guilty. The innocent person becomes less fearful, and the guilty person's anxiety increases. Gordon, who teaches courses on interview techniques, says experienced questioners use many tools to be effective. Among them: Icebreakers. An interview usually starts with some icebreaking chitchat unrelated to the investigation. This allows the interviewer to get a sense of the subject's style: things like verbal tics, amount of eye contact and physical mannerisms. Non-verbal cues. When discussing the case, the interviewer looks for non-verbal behaviors. A deceptive person will often put a hand to his eyes or mouth to obscure what he's saying. A truthful person usually exhibits mannerisms that clarify what he's saying, like touching a hand to his chest and making eye contact when stating his innocence. Set up two chairs. Gordon recommends placing two chairs facing each other so that the interviewer can see the subject's entire body and there's no object behind which a subject may hide.Consistent questions. With multiple subjects, the interviewer should avoid accusatory questions and ask each one the same set of questions, and should use a consistent reading and writing style. The questions should either be all read off paper or all memorized. Every response by the subject should be written down. (Selective recording invites a subject to analyze the interviewer's behavior.) Anyone else in the room must be silent. If a manager or an HR representative is present, that person should sit behind the subject and stay quiet. "I tell them they can sit in under one condition," says Gordon. "If they think I've asked an improper question, they should say, 'Mr. Gordon, can we step outside?'" Other than that, they have no input."