My name isXXXXX have been a licensed attorney for over ten years and will be assisting you today.
I am obligated to only provide legally accurate information in response to your question. In all cases in all states, there is a policy preference for finality. That means at a certain point, no court
has the authority to review the case. Procedurally, there is nothing more to do directly with your cousin's case in the courts due to the passage of time.
Beyond that, however, if you can show there were facts or circumstances that would prove his innocence, I would suggest you consider contacting the governor's office regarding a potential pardon or commutation. There is no time limit on that.
A pardon is just what you would expect. Forgiveness from the governor and release from custody. A commutation is slightly different and means a shortening of the sentence
Information on the process can be found here
The forms are here
If you have more questions please feel free to ask. I'll be happy to answer them. If you do not, please do remember to rate my service in assistance to you today.