Abilene (WBAP/KLIF) – A male inmate killed a female corrections officer this weekend at the Robertson Unit, a maximum security Texas prison near Abilene. 55 year old Mari Johnson was found unresponsive about 3 a.m. Saturday near the prison’s kitchen area. She was dead on arrival at an Abilene hospital. Johnson had been a prison employee for seven years. An investigation into the circumstances of her death is underway, so very little information is available on just what happened. The prison system has not even identified the inmate it says killed her.