Perhaps we should stop to consider that the entire principle behind punishing crimes is to stop them re-occurring and to punish the criminal. Once a person has served his or her sentence, he or she re-enters society and is deemed to have atoned for their offence.
This is the theory, and abiding by this, obviously, if we know the person's history we should try to forget it, and treat them as we treat any others we meet.
I realise that there is a great gap between theory and practise, in that not all who serve a prison sentence have to use a very old-fashioned term "seen the error of their ways".
However, if law-abiding people ostracize those who have been found guilty of an offence and served their term, when they are returned to society, we surely leave them little choice but to continue to be around former criminals, or those still living by crime.
So, to me it seems only fair that we should try to treat people as we find them, We all have acquaintances who never become more than that, and some whom we drop quickly because we do not feel any desire for their company. This must surely apply to those who have a murky past as well as to the blameless.
Personally, I would reserve the right not to try to get to know someone who had abused a child, or committed rape or murder or any other atrocity. But I cannot rule out the possiblity that I, unknown to myself , have been in contact with those who have done these things.
So surely the way forward is to take people at their own evaluation - do any of us tell a casual acquaintance all the details of our past, or indeed or present?
I have never been in conflict with the law, but I do not go around telling people whom I voted for in the last general election, the intimate details of my life. or that I am a regular church-goer. This being so, I can hardly expect a new member of say a book club to announce that he has just been released from Barlinnie!