From what I understand you typically need a &#x27;base-line&#x27; of normality to know when someone has deviated from that. People can get nervous or make mistakes at any point. The best way to set the base-line is to have a general conversation to put them at ease and then ask the more consequential questions. This could lead to longer queues though which would be an unfortunate side effect.<p>TL;DR<p>Use the deviation from the base-line to work out if someone is lying.