I have got hacker PC with encryption password. I have everything 100% if someone wants to get money back it's possible. One detail was strange because, hacker keeped 1000 BTC in his wallet and all other sent to someone else. So I think he have got 1k BTC for his dirty job and invested it in another company. Maybe he just sent other money to cold storage, but from all other details (some jabber conversation) I see he just got 1k BTC.
Wait, how come you have that hacker's PC? And to think that you had the password. You also have access to his wallet? Since you said you can give back someone's hacked btc?
OP, your claims are serious and complicated at the same time. Since there are also malicious conversations that serves as a proof, I wonder why support isn't responding to you. Maybe you can also share here which project did he scam? Or more details to come up with.