This is NOT what’s likely happened, how could they be sophisticated enough to pull of this type of hack yet send it to a KYC/AML exchange in America…
* Someone working for the FBI has many Bitcoin laundering/mixing services on the darkweb who are actually working for the FBI, which the hackers were trapped into using. And then without revealing the process, said “the FBI has the private key to the hacked bitcoins”.
* Or a security team working for the FBI managed to hack DarkSide, using clues from the communications/negotiation between the hackers and their victims via surveillance programs… and through analysis of their decryption software etc. Then managed to hack them via some backdoor and sent the bitcoins to the FBI, which then led to the seizure warrant “against” the FBI.
I believe 1. is more likely, that a honeypot was setup, or 2. they got compromised somehow in a hack. But I don’t believe they stupidly sent the bitcoins to a coinbase account.
In particular read points 33-35. The hacked bitcoins where in the “SUBJECT ADDRESS” and had not been moved since, hence in possession with the FBI who had this seizure warrant against them from law enforcement, no where does it say this is against coinbase or any other exchange: