Is it possible to do this? If I send bitcoins to someone, and I don't tumble, they have a straight path back to the address I bought the coins with. Let's say I connected my bank account to realcoins.net (not real) and bought the coins there. Now they have that bitcoin address I used. Is it possible for them to identify me since all they have is an address? Would they have to call up realcoins.net in order to get the info from them? (unless they were LE, I don't see them complying)
LE can yes absolutely.