From Our Sunday Visitor (subscription required) comes an interesting question and answer.
"Question: I am an inmate in a state correctional institution. I find it scandalous that some inmates are allowed to be extraordinary ministers of holy Communion at Mass. Is it really acceptable to have inmates act as extraordinary ministers? After all, none of us is here for anything noble.
— Name withheld, Waymart, Pa.
"Answer: If there is a real need for them, such that Communion would be unduly prolonged without them, then the Church generally allows for the use of extraordinary ministers of holy Communion at Mass. Accordingly, such ministers might be necessary at Masses in a prison if the Catholic population is very large.
"In general, those who are chosen to be extraordinary ministers of holy Communion must be people of solid faith, have a firm belief in the Eucharist, be regular participants in the liturgical life of the Church and — not least — be people in good standing in the community and recognized as among those who live out the Faith in their daily lives.
"Can prisoners who have committed crimes fulfill the requirements for being an extraordinary minister? I suggest they can. If a prisoner has truly repented of his or her crime, seeks to live the Christian life within prison, and is accepted by his or her fellow Catholics in the prison as a model inmate and a man or woman of virtue, then there would be no good reason not to depute him or her as an extraordinary minister.
"You say that you find it scandalous that some inmates are extraordinary ministers in your correctional facility. Your objection would certainly be valid if the people chosen for the ministry of Communion did not fulfill the requirements I just outlined. But if they do fulfill them, then it is important to recognize that Christ calls broken and imperfect people to do his ministry in the world — in prisons, as well. Express your thoughts to the Catholic chaplain in charge, and he may be able to relieve your concern."