Where do we see the reference where the FBI got access to the server the hackers used? Is there a link to follow and read?
SO many things come up actually, we can think of a lot of things including the government owns mixers or probably conspire with the exchange the hacker used. If you can consider yourself reliable for correcting the misinformation you might as well enlighten us with a link.
Forget about all the "investigation journalists", here are the legal documents released - but even with those we can't be sure that the FBI got the key from a seized server. I'm actually leaning on the opposite.
https://www.justice.gov/opa/press-release/file/1402051/download - This is the warrant. It mentions a location - Northern District of California - where some people believe refers to the location of a Coinbase's server.
But prior to getting that warrant, the FBI already stated they have the private key "in possession" in the affidavit -
https://www.justice.gov/opa/press-release/file/1402056/downloadNote that on page 7, paragraph 34 it says
"The private key for the Subject Address is in the possession of the FBI in the Northern District of California"
It is very likely that the location mentioned in that warren refers to a facility where the FBI stores the private key in.