Newly released documents show a University of Colorado police officer did little aside from check theater shooter James Holmes' background after his psychiatrist shared concerns about his homicidal thoughts.

The campus officer also deactivated Holmes' campus access cards. The psychiatrist declined to detain Holmes, who had revealed no specific targets or threats, because she thought it would only "inflame him."

The documents released to The Associated Press in response to an open-records request provide the most detailed look yet at how university officials handled concerns about Holmes, who dropped out of its neuroscience program about a month before the July 2012 shooting. Experts say they also show how hard it can be to predict who will turn violent, even when they've displayed warning signs.

Holmes was sentenced to life in prison for murdering 12 people in the attack.