For other people who want to prevent people losing their money to a fraud, Rossi's background, including his arrests, his fake degree, his tirades, and other odd behavior are relevant.
From Stauffer: “For if a confrontation of witnesses yields statements that agree on some points, then these points must represent facts accepted by both sides. This principle certainly holds true if the historical traditions of the two groups of witnesses are independent of each other. But it holds true almost as completely in cases where the traditions intersect. For it is highly significant that the witness for the prosecution admits that the witness for the defense is right on certain points; that he agrees with his opponents about certain common facts.”