Yet Hardin's main notoriety in the Sutton–Taylor feud came from his part in the killing of two lawmen known to be Sutton family allies. On May 17, 1873, in Cuero, Texas, Hardin killed DeWitt County Deputy Sheriff J.B. Morgan, who served under County Sheriff Jack Helm (a former captain in the Texas State Police and leader of the Sutton force at that time). Later that day, Hardin killed Helm in the town square of Albuquerque, Texas. On the run again in June 1873, Hardin assisted in the escape of his brother-in-law Joshua Bowen from the Gonzales County, Texas, jail where he was imprisoned on an 1872 murder charge. Allegedly, Hardin was also involved in this killing of Thomas Holderman.