She took him shooting with her, and trained him at a time when a reasonable person quite likely ought to have known that he was mentally unstable. If she kept her guns locked up, obviously the degree of security employed was insufficient. She didn’t deserve to die for that lapse in judgment, but neither did a host of innocent children. We’ll certainly find out more in the near future.
A lot of this is hearsay, we should for the actual facts and not speculate.