here's a piece that I find relevant:
those who knew him were shocked saying he was not the type of individual to hurt another
I don't know if this type of thing can ever actually fully be prevented...people snap and break sometimes
No you can't bubble wrap the world, although it seems sometimes as if some people may want to. But the investigation is important here because it will be impartial, a logical and reasonable assessment. Even if the investigation finds that something could have been done to intervene, it doesn't necessarily imply a larger fault unless it can be determined that someone, somewhere should have been able to foresee it. Many times, it's the tragedies that make us evaluate the 'way things have always been done' and conclude that may not have been the best way to do it.