If you do *nothing* then it's legal. You are under no positive duty to report crimes, and you cannot be charged as an accessory merely for failing to do so. Even if the police question you about the murder, you are within your rights to refuse to answer their questions.
You have to tell the police some things, like your name and address if asked. But beyond that, you are under no legal obligation to talk to them. The only way you would be legally compelled to talk about what you saw, would be if someone else is charged and a court orders you to appear and give evidence.
I'm not saying you shouldn't report it (indeed I think you absolutely should) but it's not illegal not to. You're not obstructing justice or being an accessory to the crime simply by doing nothing at all.
No. Not unless you had some kind of heightened legal duty. If you were just walking by, that's not your problem... but you should always do the right thing.
Think about the victim and their loved ones. Wouldn't you want someone to step forward if they had information about who killed someone you cared a lot about?
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.