Shemiras Halashon Halachos
Hilchos Lashon Hara chapter 7, section 10 If there are devarim nikarim, clear indications the story is true, the law is as follows. If the story even if true can be judged favorably or if it involves lack of good traits or other details explained above in paragraph 7, the principle of devarim nikarim is irrelevant. For we must certainly judge the person favorably if he is an average person and not feel disparaging towards him. If there is no way of judging the matter favorably one may believe the report.
Hilchos Lashon Hara chapter 7, section 11 12 This is only if the indications are very clear, that is, close to the story, and if one saw the indications oneself. If the indications are distant and only slightly relevant, or if one did not see the indications oneself but only heard them from others, this provides no advantage at all.
Even if their are clear indications, this only allows one to believe the story oneself. One may not repeat the story to others as it is no better than seeing the incident oneself which does not allow one to relate it as explained earlier (4:3,4). Also, this leniency does not allow one to cause the person financial loss or to strike him.