Colorado police officer recounts finding, arresting Aurora movie theater shooter

COLORADO -- A police officer testified in the Colorado theater shooting trial that he was in a parking lot just 20 feet from James Holmes when he realized Holmes was involved in the attack.

Aurora Officer Jason Oviatt was the first witness called Thursday on the trial's fourth day.

Oviatt says he first thought Holmes was another officer because he wore a gas mask and helmet, and police had been warned to wear masks because of gas inside.

But, he says the other officers were looking for a way into the theater while Holmes was standing beside a car, looking relaxed.

Oviatt and another officer arrested Holmes.

Holmes is charged with killing 12 people and injuring 70 in the July 2012 shootings. The defense acknowledges Holmes was the shooter but says he was mentally ill.