On 20 July 2012, the 27-year-old walked into Aurora, a Colorado movie theater and shot dead 12 people while injuring 70 others.

The shooter was dressed in riot gear, carrying three guns and more than 700 rounds of ammunition into the Denver theater during a midnight show of the the Batman film The Dark Night Rises.

"Initially charged with 24 counts of murder and 140 counts of attempted murder — two for each person killed and two for each injured, Holmes was also charged with possession of explosives", the Colorado Springs Gazette reported.

Holmes had entered a plea of not guilty by way of insanity during his trial.

The plea was refuted by District Attorney George Brauchler and the prosecutors sought the death penalty on 4 June 2013.

"He only stopped when the gun stopped… We know what insanity is… this ain't it. He knew what he was doing when he killed those people. He intended to kill them. That was his specific goal", the District Attorney said.