I think there is a very simple thing to put him in a corner:
Everybody, so that is worldwide in this cryptoworld, go to the police and make it official you have been robbed.
OK if only a few persons do it it is nothing, but if a lot people do it worldwide, there might be a big chance that at airports / bordercrossings etc etc they will get a message in their system as soon as his name shows up.
Then slowly the ball gets rolling.
And in this case i hope they catch him in a country somewhere in asia.
Assuming CoinEX never comes back, I think the best bet (for American victims at least) would be to report this issue to the
Internet Crime Complaint Center. I'm not sure if foreign victims are allowed to file reports, but it doesn't hurt to get as many testimonials involved as necessary to ensure justice is served. Those with additional information regarding the identity of the perpetrators will be a big help in speeding up the search process for them. There's enough money and victims here that it would be hard for them not to pay attention to this case. Unfortunately, the FBI doesn't disclose the details of what they do or if/when they find said criminals, but it's better than leaving it to the phantasmagorical realm of 'assassins.'
Bringing it to the feds may leave a bad taste in the mouths of certain crypto anarchists, but reality has to hit home eventually.