As many as you like. Ideally each one should speak for itself.

[b]Edit:[/b]

One of you sent me some suggestions, and I gave this guidance, which might be useful for everybody.

[quote=@Jig]
I'd rather it be a physical object. It could perhaps be a written testimony, but there would need to be an actual manifestation. Again, similar to Clue. ♫ [see note below]

The more the object speaks for itself, the better. Like, if it were a murder weapon, that's pretty obvious. [REDACTED] might need a little more explanation, and the less explanation, the better from my standing. It should be something that if your character sees it, they'll understand immediately what it is and basically go 'oh crap'.[/quote]

[url=https://www.youtube.com/watch?v=cDDdeHtrxfA]Clue[/url] is a brilliant film that has more than just a little bit inspired this game in plot, if not in tone. Yes, it is based on the board game Clue (or Cluedo, as it's called over here).