Let me make this clearer. NOTHING will keep the technicians at IBM Labs from removing your disk in a clean room from the drive, removing the layers one at a time, and retreiving any information that was ever put on the drive. NOTHING.
The last time I talked to them it was approx $10,000 an hour with a two hour minimum. But that was two years ago so the price may have changed.
Your local prosecutor probably won't spend that much time and money to do this. But it CAN be done.