Hilchos Lashon Hara chapter 7, section 11 12

This is only when the signs are really clear: they are connected to the story itself, and he saw them himself. But if they are far from the story itself and only a little connected, or if he did not see them himself, the signs do not help at all, and it is forbidden to believe.

Even really clear signs only allow him to believe the story himself. They do not allow him to go and tell other people; that is forbidden. This is because even if he saw something bad about a person with his own eyes, it is forbidden to go and tell it. And in no way at all is it allowed, based on clear signs, to cause the person to lose money or to hit him.