7 months after closing the owner's son has no claim to anything left on the property. If the man enters your property again, tell him to leave or you will call the police and report him as a trespasser.
Unless provided for in your purchase agreement or some other agreement to the contrary, the items he left behind are yours.
Any answer provided is for general informational purposes only and is not intended to be legal advice or a complete discussion of the legal issues. This answer does not form an attorney-client relationship. Each individual's situation is different, and you should seek independent legal advice from an attorney familiar with the laws of your state.