How to Revoke My Invitation for a Non-Immigrant Tourist Visa

Hello,
I have decided that I do not want to sponsor/host a friend who is applying for a non-immigrant, tourist visa to visit me in the United States.
I now have reason to believe that this relationship is based upon a scam, and that my safety could be in danger, and that of my friends in another country, if I confront the issue directly. The person is setting up an interview date. The person also has a copy of my passport for documentation, as well as letters from me inviting him. He also has a statement from my bank, with the 4 last digits of my bank account.

Is there a way for me to inform the US consulate that I am not in support of this tourist visa, and that I will not be responsible for him, if they enter the states? Without the person finding out? I do not want my identity to suffer as revenge.

My hope is that he simply gets refused. Can I anonymously do anything to make sure he gets refused?
Please help....and advise.

Thank you!
Janey

Presumably their interview will be at a local consulate. I suggest you contact them.