u/Disastrous-Week-8104

What type of attorney or reporting avenue should I look for? Possible forged LLC demand letter / harassment pattern

I am not asking for legal advice on the merits of a business dispute. I am trying to understand what type of attorney or reporting channel would make sense for this situation.
I co-own an LLC with another person. I recently received a mailed letter that purported to be from that LLC. The letter demanded money from me for allegedly using the LLC’s name, accused me of alleged federal crimes, and threatened to report me to authorities.
The issue is that neither I nor the other authorized person/manager of the LLC authored, approved, or authorized that letter. I have a signed statement from the LLC manager confirming that the LLC did not authorize it.
There is also evidence that a specific individual had sent a PDF version of that exact letter to another person about a week earlier, saying he was going to send it to me. A week later, I received the physical letter in the mail.
This is not happening in isolation. The same individual has allegedly engaged in a broader pattern of intimidation/harassment toward me, including anonymous emails, doxxing attempts, showing up at my residence, and threats.
I went to the police station and tried to explain this, but the person I spoke with treated it as simply a civil demand letter/business dispute. I understand that a normal demand letter can be civil, but my concern is that this letter may have falsely used the LLC’s identity, demanded money, threatened criminal reporting, and was part of a broader harassment pattern.

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