what can I do to protect my mother from a scam artist?

my sister just died, and I think a man in mom and my dads life is scamming them. He owns slum hotels in WV and FLA and is ';being so gracious'; to have my parents get a loan for him for 15 thousand, he says they will be ';silent partners'; and acts as if he is doing them a favor by keeping them off the books so they dont get taxed.I have until febuary to stop it and the only way would be to discredit ';buddy';. Any help would be greatly appreciated, and how would I go about getting a check ran on the guy and his slum hotels? what can I do to help my mother get money documented so they dont get taken.