A surprise 8 a.m. raid by Japanese authorities, marching into troubled cryptocurrency exchange Coincheck Friday (February 2) morning.
Hackers stole $530 million dollars worth of customers' digital money last week, one of the world's biggest cyber heists.
Now officials want to pin down how they pulled it off.
Finance Minister Taro Aso said regulators shook down the office with security checks and Japan's financial regulator revealed it had urged Coincheck to fix vulnerabilities well before hackers made off with the virtual cash.
Security gaps were part of why the exchange had never actually been given approval to operate.
Japan last year became the first country to try and regulate exchanges on the national level.
However Coincheck, like many other Japanese exchanges, was given official leeway and continued to do business as usual pending registration.
The exchange says the coins were stored in a "hot wallet" connected to the Internet instead of a more secure "cold wallet" operating offline.
Meanwhile on Friday (February 2), Bitcoin, the world's largest digital currency, continued to slide below $9,000 from a peak of $20,000 in December after a Facebook ban on cryptocurrency ads spooked investors.