[willj]

Can you give us more reason as to why you're 100% sure the paper was not accessed? You don't need to tell us where it is/was, but your extreme certainty in that fact seems greater than the certainty I have about almost anything in my life.

Another possibility no one has mentioned yet: is it possible your nephew is lying? Perhaps he "stole" the cryptocurrency from himself, and went to his relative hoping they might give him pity money to get him back on his feet? Just a wild guess.

[fadys]

I have the transfer-to addresses. The thief has done this multiple times...for 7.5 BTC too, in one instance. He's not lying and has never been known to lie.

I'm sure in the same way you can be sure that if you were tasked with doing the same thing, you'll feel 100% confident that no one would be able to access that paper. And even if they did, they wouldn't know what they were looking at.

[sigmaprimus]

Why would a thief use the same address more than once? Especially one that is sophisticated enough to do what You have described? Is it possible that the address in question is a public address pointing to a gambling or tumbling service? Have You Googled it?