You have not mentioned if there is any departmental inquiry or disciplinary proceedings are pending against you.
You have stated that you have resigned from job but if the resignation was tendered after you were suspended then the employer can refuse to accept your resignation pending investigation.
However, if you have been served with a legal notice, then it becomes your duty to issue a reply notice denying their allegations accordingly, and if at all any suit is filed against you for recovery of their money, you can contest and challenge the same as per law and on the basis of documentary evidences in your support.
If the inquiry or the orders for suspension was initiated against you after you have tendered your resignation, then actually they do not have any case at all.
They are just trying to threaten you by abusing the power in their hand, you do not have to be worried or sacred in such an event, you can challenge all their legal actions appropriately on the strength of documentary evidences in your possession.Â
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