Good morning. I am terribly sorry for this turn of events but you have raised several issues here and I think you can take action.
First, he cannot simply keep all of your property and sell it. If he has done so and you owe rent, then you may demand an accounting for proceeds, and then recover the difference as a practical solution.
This can be done by lawyer demand as well as a lawsuit for an accounting and recovery of items
The police usually do not intervene in these cases and prefer you pursue it by negotiation and civil court action.
Martindale.com is a good source and you want a business lawyer to pursue this on commission fee if possible.
His opening a business is not actionable, unless he had signed a non compete with you. If you worked as partners, you can pursue a claim that he violated his duty of loyalty and good faith, but its a difficult argument if not a formal corporation or similar organization
He cannot defame you by spreading alse information. That can be stopped by a a lawyer cease and desist letter followed by a lawsuit for an injunction and damages.
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