Source for anyone interested. I was initially confused since New York got rid of the death penalty decades ago, but it's from a new federal charge I hadn't seen yet.
As far as I can find they haven't officially said they're pursuing the death penalty for this charge just that this charge is eligible for it. I see no other reason for it though.
Not to discredit the opinion, but don't most school shooters (if not all -I don't really pay attention) get killed on site and also have a personal grievance rather than just manipulation by media and statistics? Mangione seemed poised to become a serial killer. If he's free'd, it tells society it's ok to go around killing allegedly bad people (and ~20% of us are incredibly gullible conspiracy theorists -percent will be higher on certain sites on the internet as opposed to real life).
We also have to wonder how much more effective long term Mangione could have been alive and free.