Customers do it, and do not be fooled, some employees do it too, they buy at the beginning of their shift and have plenty of time to do the substitution later. Putting a $ 20 undergarment in a $ 5 product package is very simple and when it comes out, even if it is searched, the employee will have his proof of purchase.

To prevent : 

• Keep the product purchased by employees in a supervised area until the employee leaves.
• Install a camera to monitor the location of products purchased by employees.