More details have emerged about the attack on Aurora movie theater shooter James Holmes in a Colorado state penitentiary in October.
Holmes, 28, opened fire in a movie theater, killing 12 and injuring 70 in 2012. He was convicted and sentenced to life in prison without the possibility of parole in August.
Holmes was housed separately from the general population for his own safety. But prison officials said a guard left a security gate open just long enough for another inmate to slip through and attack Holmes.