I dont think anyone, whether your a hacker or not, would have that kind of time to sit down and create up to 1400 cryptocurrency addresses and then start moving one Bitcoin to each of them
This is not a difficult or time consuming thing to do. In a good wallet you can generate that many addresses with a single command, and then a couple more commands to generate a few pay to many transactions to distribute 1 BTC to each address. Doable in 5 minutes.
I don't know if it's possible for a mixer to cooperate with the authorities.
A good mixer, like a good VPN, should not keep logs and so be unable to give any useful information to the authorities. If your mixer is handing over your transaction details to the authorities, then I would suggest that you find a new mixer.