When an individual is lying, they typically use a part of their brain that causes their body to overcompensate or show signs of stress while they add emotion, fabricate a timeline/events and recount the false information. Since our body displays certain tendencies when telling the truth or a lie, there are ways we can study those signs of stress and signals to detect fraudulent information.
A few simple ways to identify when someone is lying in your workplace is to watch their body language as they answer your questions. It is important to instill accountability on follow-up and/or repeat your questions to understand that individual more and their stressor signals, which extends beyond a simple interrogation.
Regardless of the size of your entity, it is also important to implement thorough audit systems to detect fradulent behavior. For instance, when an employee in your payroll department observes operations on a day-to-day basis, they may uncover and be tempted to utilize seemingly undetectable loopholes like setting up a third-party vendor that is really a shell company they established themselves.