We'll never know what he could have done. If I could reasonably save the life without it being a suicide act that's the priority. If you give him the benefit of the doubt, that he couldn't saved the guy then at least his pictures could hopefully help authorities to catch the killer. There was a good point made about the mentally ill. Whenever we've had mass shootings the kneejerk reaction is to call for gun control. It often turns out there were red flags about the individual that were ignored or pushed aside for political correctness reasons. Point is, if you can save a life that's first priority (in Judaism it's called Pikuach Nefesh - the principle that saving a life overrides everything) but if you can't do that, providing key evidence to the police to catch the murderer is at least something one can do.