You will have to sue him if you want to recover your damages. You may have to hire a landlord tenant attorney in Philly--that lawyer will know how to proceed on the information you have.
You can likely recover damages, maybe attorney fees. You may have to garnish your tenants' wages eventually.
You can call your local county bar association, or use the avvo.com find a lawyer option to locate a landlord tenant attorney in your area.
Best of luck
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