Is there a possibility you tried a "BTC doubler" or HYIP scheme by that time?
The address: 37zfKL5EqsokYztEj6yrJxeJah52CgJixG is connected to a forum user: https://bitcointalk.org/index.php?action=profile%3Bu%3D778507
This user / wallet is connected to some ponzi schemes. Source.
(don't know how i could oversee this yesterday)
Probable websites (not advisable to visit them, i haven't checked for malicious activities!):
http://Bitcoincopy.site123.me
http://Multiplybitcoin.com
http://Btc48hours.com
http://mmmglobal.org/?i=lex
I can't find any related websites to the other wallets though.
Says the wallet is connected with 4 possible Hyip scams, so it's been used for illegal activity.
Unfortunately, there is simply no way for bittrex to get the BTCs back, not only because the btc transaction is basically irreversible, but also because the transaction is old enough, he sent them in 2017.
Here's my address: 373dAiDkUX6cfkadmWcbeJHbHhxpZScDP6