And I would blame his family for letting him out on his own.
Obviously doctors didn’t catch the problem, so his family probably had some warning signs, but that’s about it. His most obvious symptom was severe migraines. About 6% of American men have migraines (about 18% of women). So it’s not enough.
The paranoia is possibly more diagnostic, but as a condition itself, which could be by itself, or associated with schizophrenia. But that still needs a professional diagnosis early on.
This was probably a bolt from the blue, that nobody saw coming, so nobody did anything to stop it.