Advice on how to start

Hi, so my husband wants to adopt my daughter. He has been in her life since she was 3 she is now 8. Her bio dad is in prison and serving a life sentence and has not been in her life since she was 1 week old. My daughter knows all about the situation and has stated that she would love my husband to adopt her as she sees him as her dad and always has. Problem is we are unsure if we would need bio dad to sign off on it or if he even has rights? Or would we even need to consult him if he’s in prison ? Any advice on what to expect with our situation?