Sefer Chofetz Chaim chapter 6 halacha 10 footnote 25  

There is a difference between being concerned and taking proper precautions about something you heard and having a doubt about someone after you heard something about him or her. A concern and a doubt are two different things which must be differentiated. You can have concerns but you can’t have doubts just because you heard rumors or lashon hara.

This is illustrated from a gemara on daf 61a which tells a case of two Jews from the Galilei who rumors had it were murderers. They came to Rabbi Tarfon and asked him to hide them from the Roman Government. Rebbe Tarfon told them I can’t hide you be I have to be concerned that maybe you are murderers and the government will be out to get me for hiding criminals but I will not turn you in and my advice to you is to go hide yourselves because I can’t have a doubt that you might be murderers since every Jew has an assumption of being kosher good people until proven otherwise. This is the difference between a concern and a doubt. The Rosh asked a question how can we even be concerned that the rumors or lashon hara might be true and allow harm done to someone like if he was caught by the government?

The Chofetz Chaim has a few answers to that question in this footnote and towards the end of footnote 28. One of them is that it comes out one can only be concerned when what he hears will effect him or others like in this gemara that if these people were murderers then by protecting them it might put others in danger so can’t actively protect them but can’t turn them in because maybe they aren’t murderers. But let say the case last week of the guy who rumors say he ate non-kosher out of spite of Hashem then can’t be concerned about the rumors and not give him charity if he needs or redeem him if he is captured since it is just rumors even if he was known to be bad in other ways but just not so bad.

Another way of answering for Rebbe Tarfon was that the only reason why he didn’t save them was because he knew they can save themselves but if they couldn’t then he would have to protect them even if the government might go after him because the Torah says “don’t stand over the blood of your friend” you have to help any Jew in need even if they are suspect of doing really bad until it’s been proven they actually did it. This happens to be a very sensitive subject which might clarify how Jewish institutions seem to protect or hide would be Jewish criminals but until they are proven to be guilty of wrongdoing then we have to assume he is innocent even if he has a shady past we have to assume he has slipped so low until proven otherwise and you can’t even have doubts. However at the same time they and everyone should be concerned that the rumors or allegations might be true in order to take precautions to protect yourself and others from potential danger on any level.