What to do if I have a former employee who stole from me by using business credit card for personal use, wrote checks too herself and made unauthorized ATM withdrawals?

What you have described is a crime. You therefore have a right to contact the police and seek an arrest warrant. If convicted, you would have the right to appear in court and ask for Restitution, and the court (judge) would have the  right to order it. Restitution simply means to pay you back for what was wrongfully taken. You also have the right to file a civil suit. It can be a difficult decision so it would be far easier if you consulted with an attorney who could guide you based on what would be in your best interest to do, and when, and how.