Most mass shooter parents probably new what was going on or new there kid need mental help
Seems the Ohio guy had a life long history of crazy.
Many families have gotten them help, over and over. Keeping someone locked up is nearly impossible until they do something horrible. Often with these stories you do hear that the person had been or was being treated for mental illness.
We have to make changes so the seriously mentally ill can be locked away again. We have instead made that nearly impossible to do.