A check I didn’t sign was deposited into my account via ATM. Am I liable?

Bank A’s check was deposited into my account at Bank B via ATM. I don’t know how but I am being accused of forgery and theft. It is a co workers check that was deposited. I have no idea how but I worked with bank B to figure out the situation due to my account being held. After a amount of time they released my account. They told me they would close it if I was liable. They didn’t but now they aren’t giving me any information(bank b) on the situation. Now I have a court date and wasn’t served any summons. I found out through a job background check. Don’t have money for lawyer upfront.