Comment Yes and no (Score 1) 75
Is there a mechanism built into the bitcoin structure that allows for this and voids the coins?
Is there a mechanism built into hard cash that allows to void the silvercoins/bank bills to be remotely voided? No.
And basically any cryptocurrency works the same. There's by definition NO SINGLE ENTITY in control of the bitcoin protocol (that's the whole point of it).
so nobody could remotely void any coin. (but at least that means that legally earned crypto-mony won't suddenly vanish neither... no fraudulous chargebacks on the bitcoin network)
On the other hand, cryptocurrencies aren't anonymous. At all. In fact they are (again by definition) the exact opposite: every signle transaction is broadcasted to the whole network. That really helps the security (thus every single node on the network can check and verify all transaction) without needs for a central authority (see previous point). But that also means that anyone can follow transaction a follow money jumping from one public key to another.
As the blackhats aren't probably mining actual bitcoins, but some minor alt-coins which is much more mine-able on CPUs, at some point, they'll need to exchange it for something more easily spendable. So they need to send them to one of the (few) exchanges accepting less known coins (Probably cryptsy).
Law forces could collaborate with exchanges and try to catch transaction whose coins can all be traced back to the initial mining by this botnet.
Then it's a matter of matching transaction with profiles registered at the exchange or further following the money trail.