I cant complete the quest by killing the mage leader since I already killed him hours and hours ago so now my marker is telling me to kill a dead body and not letting me advance, any fixes other than trying to reload an old save that at this point may or may not be there for me anymore. Thanks for the assistance.

Same thing happened to me with the bandit leader on Valtheim Towers. I just spoke to Farkas about work again and it moved along.