As it turns out, it was the US government.
https://www.techspot.com/news/87487-us-government-seizes-over-1-billion-bitcoin-stolen.html?utm_source=dlvr.it&utm_medium=blogger
https://www.techspot.com/news/87487-us-government-seizes-over-1-billion-bitcoin-stolen.html?utm_source=dlvr.it&utm_medium=blogger