This has nothing to do with investigating anything. First, the public would never actually realize the reality of war without actually experiencing it, what it can only realize is what the press would choose to tell them and in a way that the press chooses to report it, and there's a real lot of wiggle room in reporting and choosing how to present events. But more importantly, this would be the same with and without investigation - the tragedy already happened, and if you plan to exploit it in anti-war propaganda, you can exploit it regardless of why it happened, who is to blame and any other investigation results. In fact, investigating may only make it less useful for for anti-war purposes - what if after investigation it turns out Taliban deliberately placed their fighters in the midst of the civilians so that the response fire would hit most of them and thus achieve the best propaganda effect? It might only make the society more determined to get those bastards. The most tragic and most shocking part already happened - people died. If you want to say war is evil because people die - no further investigation necessary. Further investigation is needed only if you intend to wage war in the future but want to do it differently - but then it is useful mostly for people that actually wage war.