Cpl. Douglas Michael Sullivan, 23, pleaded guilty Tuesday to involuntary manslaughter in connection with the death of the 19-year-old Gordon County native who had been deployed to Iraq with his Marine Reserve unit.

Robin Patterson, Warren’s mother, told the Calhoun Times earlier that she was “absolutely appalled” when she learned of the plea agreement last month.

Patterson planned to go to California for Sullivan’s court martial and is expected to testify during the sentencing phase.

Warren graduated from Gordon Central High School in 2005 and joined the Marine Reserves.

Sullivan said that he accidently shot Warren while improperly handling a weapon at Forward Operating base Trebil, near Fallujah, Iraq.