That's really for a jury to decide. It's not circumstantial when they have his device finger printed doing nefarious things at other steps of the theft process for the same amounts of money that are coming out of a coin mixer.
Are coin mixers really that rudimentary, if they are why would you bother? It seems pretty easy to design a mixer that works, logically, so can noone muster the business backing (or is it legal issues?) to do that, not even in any country in the World?
I am yet to see a single mixer that would cryptographically prove that I am not participating in an FBI scheme to mix BTC in order for them to then know who mixed what in the first place.
