Thirty-seven police officers, not identified in previous research as belonging to groups that are superior in lie detection, attempted to detect truths and lies told by suspects during their videotaped police interviews. In order to measure consistency in their ability, the officers each participated in four different tests, each of which was on a different day. They were asked to indicate their confidence in being able to distinguish between truths and lies prior to the first test and after completing all four tests. We predicted that accuracy rates would be higher than those typically found in research with police officers; that good or poor performances on an individual test would be partly caused by luck, and, consequently, participants' accuracy scores were likely to progress towards the mean if their performance on all four tests was to be combined; and that officers would underestimate their own performance. These hypotheses were supported.