Donnelly began to work for the Pittsburgh Bureau of Police in 1993. In 2002 he was promoted to sergeant. He was transferred to the Traffic Division and was assigned to the Motor Unit. He is the coordinator of the Pittsburgh DUI Task Force and a drug recognition expert. Recently, Donnelly was recognized by the Pennsylvanian DUI Association as one of Pennsylvania's "Top Guns." He was also presented an Award of Valor for his actions on April 4, 2009 during the tragic shooting of three Pittsburgh Police officers. His Irish roots can be traced to Counties Antrim and Cork.
