I don't think prisons should be avenues for murdering people, regardless of the crime. The person imprisoned is there to keep him from harming himself and others, and if he was that hard to live with by other prisoners or even guards, he should have been protected from such a fate.
This nation stands for having laws and abiding by them. People are sent to prison when they serially ignore laws and commit crimes. They are experiencing the life of people who are or should be reviewing their crime, and hopefully are given a sentence commensurate with righting the wrongs of the past by the passage of time they could have been living like free men. Lessons do not come easy for some, so that's why some of them get long stints. Death by murder does not teach a lesson to the inmate. Murder of a prisoner should be so severely punished others will think twice before offing someone they dislike or heard being disparaged by any number of sources.
Justice is not served in this way.