Indeed, there seems to be a fundamental dilemma there. Satoshi solved the problem of secure trustless e-payments, but there is still no solution for the problem of recovering stolen coins without spoiling that primary goal.
This is unsolvable. Please ponder about the definition of 'stolen' in a system where property is defined by 'knowledge of a key'.
There is no way to mathematically demonstrate that a transaction, for example, was fraudulent. Or that if two people know the same key then one is a rightful owner (whatever that means) and the other is not.