Stealing can take many forms: unauthorized discounts, bartering for services without permission, on the clock without working, use of equipment/materials/vehicles/supplies for personal use without permission, and more.
In much the same way that small business owners should share the income and profits from the enterprise with employees (giving everyone a stake in the business), owners must clamp down on stealing - since all employees and the enterprise itself are harmed as a result.
Utilize your three step warning process - a verbal warning, a written warning with consequences spelled out, and a final written warning with a required written response from the employee. This doesn't mean you can walk an employee out the door at any time, but working through the process establishes your professionalism, and becomes a benefit for all employees. While the warning process must be kept confidential between you and the employee - eventually you will need to explain the circumstances to the rest of the team. Take the needed steps to protect the rights of the employee and their dignity in the face of the situation.
Quick action on stealing will ensure the entire company works better and trust is built and maintained.
There is a wealth of information on detecting theft and dealing with it on the internet. Here's a good place to start for more information.
