The Constitution states "shall not be infringed". Ie; no restrictions. Removal of Rights as punishment requires conviction, ie; due process.
We just had a policeman killed in Indianapolis , along with a couple of other pepople, because of a situation like this. The police had even taken the guy's guns once, because he was considered a danger to himself. However, in Indiana those guns couldn't legally be kept for more than 30 days unless medical proof was shown. The hospital dropped the ball, the police had to return the guns (taken in a prior disturbance) and a week later the guy was blasting his way through a neighborhood.
If you ask me, the first thing that needs to be addressed is mental health laws and why we are allowing crazy people out on the street. This applies not only to gun crimes, but homelessness, child molestation, indecent exposure, rape, and a whole host of problems caused by letting dangerous people wander around unsupervised.
I'm fine with requiring a court proceeding to remove someone's right to own a gun. I just don't want to hear any wild tales that it's unconstitutional to do so even WITH a court proceeding.