An interview usually starts with some icebreaking chitchat unrelated to the investigation. The interviewer should avoid accusatory questions and ask each subject the same set of questions. A deceptive person will often put a hand to his eyes or mouth to obscure what he’s saying. With multiple subjects, the interviewer should use a consistent reading and writing style to ask each one the same questions, says Nate Gordon, founder of The Academy for Scientific Investigative Training in Philadelphia. Anyone else in the room must sit behind the subject and stay quiet.”]
Source: https://www.csoonline.com/article/2118074/inside-the-interview-room–investigative-techniques.html