Law about old fines

I have an employee that works for me and that was released from a MS state correctional facility and is now on parole. He served over two years for DUI. Before being sentenced he had previous fines in Hattiesburg, MS for previos DUI charges.
The city tells him that he must still pay them the fines and that they do have a warrant out for him now. I would like to know if he must still pay the fines or should they have been cleared due to his incareration.

His being in jail was not for that charge. Yes, he still has to pay the fines. Going to jail doesn't erase fines.