We examined the effect of (i) a second interviewer's demeanour and (ii) asking expected and unexpected questions on cues to deception. We predicted that liars compared with truth tellers would provide more detail to expected questions and less detail to unexpected questions, particularly when the second interviewer is supportive. Liars prepare answers for expected questions, and a supportive interviewer will encourage them to provide more detail. By definition, liars have not prepared answers for unexpected questions, and their answers to such questions will be less detailed. Participants (N = 168) appeared before two interviewers: The first asked all the questions, and the second remained silent. The second interviewer exhibited either a supportive or a neutral demeanour. As predicted, liars provided more detail to expected questions and less detail to unexpected questions, particularly when the second interviewer was supportive. In conclusion, a supportive second interviewer elicits cues to deceit.