A bitcoin stash worth $68 million was seized by German police but the owner has refused to give up his password

• Germany police reportedly seized about 1,700 bitcoin, but the owner won't give up his password.
• "Perhaps he doesn't know" the password, a German prosecutor told Reuters.
• At Saturday's bitcoin price, the stash was worth about $67.9 million.

German prosecutors reportedly are holding about 1,700 bitcoin confiscated from a bitcoin miner, but the man won't give them his password to unlock the cryptocurrency.

"We asked him but he didn't say," Sebastian Murer, a prosecutor, told Reuters. "Perhaps he doesn't know."

At time of writing, the stash was worth about $67.9 million.

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The bitcoin miner, who was from Kempten, Bavaria, was not named in the report. He was sentenced to about two years in prison after installing bitcoin mining software on others' computers, using them remotely to build a sum of bitcoin, according to Reuters.

He reportedly kept his mined bitcoin in a password-protected digital wallet, which is a common way to hold the digital currency.

Without the password, there's no way to open a digital wallet.

Read more: 4 heavyweight investing firms answer the 5 most burning bitcoin questions facing investors as the cryptocurrency sees unprecedented volatility

Last month, another man in Germany had a bitcoin stash of about $220 million rendered inaccessible because he'd lost his password. In January, a man from the Welsh city of Newport said he'd mistakenly thrown away about 7,500 bitcoin, worth about $275 million.

About $140 billion in bitcoin, or about 20% of all bitcoin, is stranded in wallets because people forgot their passwords, according to The New York Times.

As the cryptocurrency has ballooned in the last few months, locked-out owners have watched the value climb. Bitcoin hit $40,000 last month for the first time, then $41,000, before pulling back. It's since climbed again, and, as of Saturday, its 24-hour high was $39,982.81, according to CoinDesk.