TL;DR: Japanese cryptocurrency exchange Coincheck was hacked in early 2018 for more than $500 million. Accounts at the time and since have placed the blame on black hats from North Korea. Recently, however, local media in Japan uncovered what they believe is enough evidence to suggest perhaps Russians were the main culprits.
https://coinspice.io/news/half-billion-dollar-hack-of-crypto-exchange-now-thought-work-of-russians/