Fraud and Forgery of company documents by employee

Two of our employees have committed forgery of my company documents and defrauded another competitor company into paying them higher salary. One of these employees forged my company offer letter and salary pay slips to get a 60% hike from my competitor and absconded from my company with an advance. The second employee has been unethically working for both the competitor company and my company for two months and taking salary from both our organisations when it is clearly mentioned in our employee agreement that dual employment is not allowed. My competitor has fired them both I have been told after a background verification check led them back to us and we confirmed that all the documents submitted are forged and fake. I want to pursue a legal case against these people because I want to set an example in my company that taking unethical steps like this against your employer can be damaging to ones career. We want to support our employees but they need to follow rules. Please advise.