Which is more humane?

A man is sent to prison for life with no possibility of parole for murder. While in prison the man attacks other inmates or staff and kills someone else. He is given another life sentence and sent to solitary for 6 months. When the man gets out of solitary and returns to general population he immediately starts trying to kill people again so he has to be returned to solitary confinement. The man has become like a Lion- wild, dangerous, and unpredictable. He cannot ever be returned to general population. While the man is in solitary he starts to show psychotic symptoms and is obviously in great pain from going out of his mind. Solitary confinement has been shown to cause such problems. Should this man be put down like a rabid, distempered animal to end his suffering? Or should the state give the man medication to stabilize him as much as possible and give him access to magazines/books and art supplies? THIS QUESTION IS ABOUT WHAT IS MORE HUMANE, NOT REVENGE,PUNISHMENT, or JUSTICE.