In the second century, St. Polycarp, grand-disciple of St. John the Evangelist, wrote with sadness to the people of Philippi that St. Paul had evangelized and to whom he had written a beautiful letter.  The sadness was about a priest, and his wife, who had “hung up his collar” before there was such a thing as clerical dress.

Here is what Polycarp says:
“I am greatly saddened on account of Valens who at one time was presbyter among you…be chaste and honest…avoid avarice…greed….I am deeply sorry for Valens and for his wife; may the Lord grant them true repentence.”
It seems that dishonesty, unchastity, avarice and greed were the public sins of this former presbyter, and it seems that he walked away from ministry as opposed to being asked to leave.  The following sentence is instructive and an example for us on how to treat “fallen” or wayward priests.  
“…invite them back as frail members who have gone astray, so that the entire body of which you are a part will be saved.”
We are still connected to each other in and through the Body of Christ, even if one or another goes astray—even a priest!  They are not to be cast out, but invited back so that all of us can be saved.  Powerful ecclesiology and soteriology, fancy words for the study of the Church and of Salvation!
(Quoted from the Liturgy of the Hours, Vol. IV, Twenty-Sixth Week in Ordinary Time, pp. 327-28)