It's difficult to prove a negative, correct? Yet, in both these cases, a negative is assumed.
I am consistant in stating that anyone with a reasonable motive and the means must be considered suspects. Sort of a basic investigation 101 thing.
You state that since there is no direct and conclusive evidence that therefore complete innocence must be assumed. Which, as I am sure you already know, just doesn't make sense to me.
Yes, I do happen to know the Russians fairly well and the Austrian Monarchy fairly well. Is there something wrong with that?
The basic argument on your side seems to be that these people (tough Russian general committed to defeat N., and a nasty, suspious, amoral Emperor) were just too nice to do such a mean thing. Sorry but that sounds -at best- naive.