Compassion for a sick bomber

Just what is the right compassion to hold for someone who kills 270 people? If the compassion is because they are sick, then shouldn't we have that same compassion for the sickness in their mind that caused them to do such evil? I can have such a compassion for Mr. Abdelbaset Ali Mohmed Al Megrahi for his sicknesses ... both of them. And I do have such compassion. But this compassion does not justify releasing someone from prison. If it did, then we should release all who are sick with a terminal illness from prison. And every terrorist is sick. And it is a terminal sickness. Would we release them all? I think not. We can have compassion for the human being but not for the evil that infects.