It's a mystery where you have to try and put together different pieces of evidence, match things up, try and look for hidden connections - a certain type of human mind (mine, I guess) just finds that process rewarding.
I've gone down most of these rabbit holes and my 2c is it's one of these two people, not any of the most common candidates: Len Sassaman or Paul Le Roux.
Sassaman is dead and Le Roux is in federal prison in the US, which explains why the coins haven't moved