Since it was a criminal case you are not required to send any legal notice to the employee under forgery.You may initiate police action against such employee by lodging a forgery and misuse of official property of the company.

The proposed action may depend upon use of signatures by the concerned person and the loss suffered, if any, by the organisation as a result of this forgery. If no loss was caused as a result of this forgery, no action may be maintainable.

you may take an action against the employer for forging the signatures but u need to mention for what purpose the signatures were forged. in case the forged document was not used for the purpose of cheating or some valuable gain, the case is weak.