.... is there anyway we could find out?
Maybe spend months and years tracking thejr activity until they make a mistake.
...
but in case of Bitfinex, it would be nice to know who has control. 90k+ coins is a lot...like if they are "lost", seized or still in control of a criminal, would be interesting.
Are these different from the seized BTC by the US Justice Department from the apprehended couple recently? There are plenty of discussions in this forum weeks ago. A lot of news articles also came out.