Okay, my last reply, and I do not mean to insult anyone, if you feel comfortable in writing to prisoners, and it has nothing to do with one's colour or creed, then go ahead.
Just keep in mind the victims of the prisoners, the children raped and/or murdered by them, the adults too, so much more, but I'll shut up now.
But if you are concerned with their loneliness, talk to the victims, the families of victims, etc. and then you may be able to see both sides of this.
Sorry, that you feel sorry you brought this up.

Lots of luck with your endeavors,

DE