Alexander Vinnik, 38, has been arrested in Greece. He is suspected of running a large-scale money laundering operation focused on Bitcoin. Over $4 billion USD is said to have been trafficked through the operation since 2011. The MtGox hot wallet private keys were stolen by a hacker in September 2011. Over time, the hacker regularly emptied out whatever coins they could spend using the compromised keys, and sent them to wallet(s) controlled by Vinnk. The hacker also laundered coins from Bitcoinica, Bitfloor and several other thefts from back in 2011 and 2012.”]
Source: https://blog.wizsec.jp/2017/07/breaking-open-mtgox-1.html