South Dakota Inmate Executed Last Night | Video| 10/16/2012
His last words, spoken to the warden, were, "It is done."
Robert was convicted of beating a prison guard with a pipe and covering his head in plastic wrap to kill him during a failed escape attempt in April 2011.
Those who oppose capital punishment held a vigil outside the South Dakota penitentiary Monday night. They sang songs of peace, and many prayed for Eric Robert and the family of the slain correctional officer.