It is pretty disheartening to think that you are good enough to give
someone a job, and they then steal from you and bring your business
to a point of collapse.
Several times year I am required to install cameras to combat staff theft. In just about all cases this has resulted in prosecution or internal proceedings and dismissal. You need to make sure you have "dotted your i's and crossed your t's" so to speak when it comes to dismissing an employee, so a sure bet is to film them in the act.
I am also a licensed Private Investigator, so can help with interviewing or other matters you are not sure about.
You may also click this link for more advice re safety in the workplace.