Sorry, but in my state even if an agent knows something like this, they cannot legally tell you. I suggest you google Megan's Law. All we can legally do is suggest you contact the local law enforcement authorities with questions such as this. Whether or not I agree with this law or any other, it is the law and I follow it. :( Copied from our standard residential contract:
Meganâ€™s Law: The Buyer and Seller agree that the Listing and Selling Broker and all affiliated agents are not responsible for obtaining or disclosing any information contained in the South Carolina Sex Offender Registry. The Buyer and Seller agree that no course of action may be brought against the Listing and Selling Broker and all affiliated agents for failure to obtain or disclose any information contained in the South Carolina Sex Offender Registry. The Buyer agrees that the Buyer has the sole responsibility to obtain any such information. The Buyer understands that Sex Offender Registry information may be obtained from the local sheriffâ€™s department or other appropriate law enforcement officials.
I am sure your state may have a similar section on the paperwork/contracts you signed. The agent should have covered this with you as you & they were filling out the contract. The fact that the agent is related to the person in question does not change the law. Again, sorry :( but the law is the law.