Hire an attorney immediately. You should be concerned if the Federal Gov't is involved. I would not spend any more time trying to get answers on this site or any others. This is a complex litigation issue that needs hands on immediate attention. Good luck my friend,
Get a lawyer and fight the allegations. You will need to work with a lawyer to develop what happened and point to the real hacker who did it.
Most lawyers will give you a free consultation if you ask for one. We do this all the time, but remember that our time is valuable and you should stay with the people who help you the most.