Murder is the worst crime that a person can commit. If the murderer is sane, then you have to wonder how they became so demoralized that they could commit such a crime. I feel sorry that they somehow missed the boat on the fact that are other ways to resolve a problem. If they are not sane, then actually they are not responsible but are going to have to pay the price of confinement for something they could not control.
We should not feel sorry for murderers. Killing someone is one of the worst things that a person can do. There is no excusing that type of act. A murderer deserves any type of criticizing and hating thrown towards them. If murderers do not like the hating, then they should not kill.
This isn't an either/or situation. We shouldn't hate murderers, but we also should show them overt amounts of compassion. Instead, we should put all that energy into figuring out how to keep people safe and prosecuting the murderers themselves so they do not have the chance or ability to murder again.
In no way do I think that we should feel sorry for murderers instead of hating them. Look at the poor innocent kids and teachers in Connecticut at Sandy Hook. They didn't deserve to die and had their whole life ahead of them. Why should we feel sorry for the murderer? He should rot in hell.