Police seize $60 million of bitcoin. But where’s the password?

German prosecutors have confiscated more than 50 million euros ($60 million) worth of bitcoin from a fraudster. There’s only one problem: they can’t unlock the money because he won’t give them the password.

The man was sentenced to jail and has since served his term, maintaining his silence throughout while police made repeated failed efforts to crack the code to access more than 1,700 bitcoin, said a prosecutor in the Bavarian town of Kempten.

“We asked him but he didn’t say,” prosecutor Sebastian Murer told Reuters on Friday. “Perhaps he doesn’t know.”

Bitcoin is stored on software known as a digital wallet that is secured through encryption. A password is used as a decryption key to open the wallet and access the bitcoin. When a password is lost the user cannot open the wallet.