Adam Lanza, James Holmes, George Bremer, John Hinkley, Jared Loughner, the list just goes on and on. People who had significant mental illness, who were allowed to continue without mental treatment until they simply snapped.
And you are worried about taking guns away from people like that, because it might "violate their rights"?
Sorry, I am more worried about my right to life and safety then of somebody with a mental illness. Nor am I concerned with the rights of a felon, no matter what their crime is. They broke the law, now they get to deal with that decision for the rest of their life. Because as far as I am concerned, they broke it once, no reason to expect them to not break it again in the future.