Employee very abusive and threatening what can be done

Dear Ma'am/Sir, We are a start-up based in Bangalore. We have a Senior employee has become very abusive for which he has been reprimanded but not sacked. He has taken the office laptop with him even when asked to leave it behind and has not given any resignation letter. He has threatened the management for dire consequences where he said he will use his brother a Police Inspector to file false charges and haul us off to the police station. He also threatened to use his father a builder who has connections with police, bureaucrats and politicians to settle scores. We have not cut any pay and have paid all his dues till date. We request your kind advise and help With best regards