Something to keep in mind for after he is sentenced: the primary reason this occurred was not Florida's gun laws and not a lack of mental health services in the schools (I think this covers talking points by both the left and the right), but that school administrators, counselors, and law enforcement failed to remove a violent student with a long history of violent victimization and disturbing behavior from its school system. As with adults in our criminal justice system, we employ the 25 strikes and you're out principle and wait for a violent miscreant to kill someone before we isolate them the innocent. This sort of avoidance and covering up is standard operating procedure in public schools. I have witnessed it many times. If there is one thing our public school districts are competent at, it is concealing the depraved behavior committed by disturbing students within their walls.
The father of one of the victims chronicled this in 2019 in a book he wrote. He was relentless and did a lot of digging, all with the school district trying to hide as much as they could.
Link: https://www.tampabay.com/florida-politics/buzz/2019/09/10/parkland-dad-andrew-pollack-publishes-book-with-new-details-about-shooters-red-flags-before-massacre/