Uncanny Ability

We have a guy at the airport who somehow knows how to identify people smuggling. Nobody knows how he does it. He doesn’t know how he does it either. He is not highly educated but 9 times out of 10 he will be right. He has been doing this for 20 years. There was one time he was convinced one guy was smuggling but we could find nothing. We held the guy for 48 hours, searched everything, found nothing. But our guy was convinced. Finally we noticed that he had some cargo, machine parts. We took it apart and found nothing. But finally we noticed a discrepancy between the declared weight and the actual weight. We had to tear the machinery apart and we found the drugs. Now we have 2 highly educated officers accompanying him to try and learn how he sports these things.