Now they got all BTC from the private keys generate on ChipMixer website, even the ones that were given to us, so it was our property not on CM website. How can we get it back? Isn't this legal?
If you think this is illegal then ask the court that the government took your money from an unlicensed money service and let the law take its course.
Unfortunately, this service is illegal, and therefore the transactions that were conducted are not covered by the law, which makes any legal action difficult.
I do not know what the laws are in the United States, but if you are in a house and this house will be used for illegal purposes and it is your property, then the kingdom has the right to confiscate this property to the state.