Guard Captain Rodney is usually located in the Rivertown Barracks. If, however, you told him about Carl during the quest Skeletons in the Closet, he can instead be found at Jackson's Farm. He will remain there until you witnessed the arrest.

He is part of the quest Skeletons in the Closet. He is also the person to turn in all the quests from A Hunting We Shall Go, found on the wanted board in the Rivertown Barracks.