As long as he is a Muslim, you must pray behind him! These are all allegations that were not proven and it is a sin to talk about them without witnessing them or proving them as Allah will question all those who spread such allegations on the Day of Judgement.

Can i pray behind an imam who is notorious for so many kinds of sins like adultery, theft, child sexual abuse and so on. Little detail about him. Once local council safe was stolen . And their were three suspect. Among them one person agreed their sin and told it was done by the three of them together. Including the notorious man( imaam). By the imaam refused, so he did not recieve any punishment from local court. Another case. Once an unmarried women gave birth to son. Due to tht act authority questioned her. She told the father of that son she gave birth was the notorious man. . But the man refused when authority questioned him. Another case: The notorious man is a little bit famous for black magic. Once a local went to him( notorious man) to do something to protect his house. So , the notorious man made something from wood and wrote something in it. And told to lacal man to hang this in his house so tht any affliction will not come. Sometimes Our masjid imaam preferred him (notorious man) to lead in congregation because he is very good quran reciter. If this notorious man is in the front row, our masjid imaam will call him and handover him to lead the prayer. Here is my question: what should i do if the imaam preferred the notorious man to lead prayer? Can i pray in congregation while intending to myself tht im praying alone?