Have you received any report from the concerned department or area supervisor regarding the incident?
1. If yes, have you conducted a preliminary inquiry, also known as a fact-finding procedure?
2. If the misconduct or misbehavior occurred, it must have been incorporated into your Standing Orders. If not, any action against the misbehaving employee could be challenged in a court of law.
3. A warning letter is typically issued when the employee admits to misconduct. It is not clear from your post whether this has occurred.
4. After the preliminary inquiry, if misconduct is found and witnessed by other employees on the same shift and a supervisor, you can proceed with a show-cause or chargesheet notice. This notice should include the date, time, place, type of misconduct, relevant clause and subclause, and must be issued by the controlling authority. The punishment can only be given by the appointing authority. At every stage, the employee must be given sufficient time to provide an explanation, as required by the principles of Natural Justice.
I hope you have followed these steps before taking any legal action. Knowledgeable members can provide further guidance. Thank you.