What actual evidence do you have that he was murdered? I think it is much more likely that someone who was going to be in prison for the rest of his life, and who previously attempted suicide, killed himself rather than being murdered by someone in the prison. There is footage of the guards falsifying time sheets, so to me it seems like a pretty clear case of negligence. I recall reading an FBI report about the suicide, where they said that they watched footage of the outside of the cell at the time of his suicide, but I can't find it back.