James Holmes hearing may reveal "difficult" evidence

(CBS News) In Colorado, the suspect in last July's movie theater killings returns to court Monday.

James Holmes will listen as prosecutors detail the evidence against him. It's information that up until now has not been released.

Holmes is accused of opening fire in a crowded Aurora movie theater July 20, killing 12 people and wounding 70.

Complete Coverage: Colorado Massacre
James Holmes is mentally ill: lawyers

Only radio transmissions between first responders that night have been made public so far. The new evidence could include testimony from victims and witnesses, as well as video and 911 calls from inside theater 9, where the shooting happened.

The district attorney has warned victims' families they might not want to attend. In a letter, he asked them to "carefully consider whether or not you think that you are ready to be exposed to potentially difficult information at the hearing."

In order to keep the public and press away from victims and families who do attend, officials have set up a separate courtroom where they can watch the proceedings on a closed circuit feed.

Jessica Watts
Jessica Watts
CBS News

Jessica Watts will be there. She's attended every hearing so far in honor of her cousin Jonathon Blunk, a husband and father of two who was killed inside the theater.

"I had made a promise to him right after the shooting. I visited the crosses and told him that I would see this through to the end," she said.

Holmes attorneys will challenge the evidence. They are also ready to call their own witnesses to describes Holmes' mental state, likely setting up an insanity defense. At the end of the week, the judge will decide if there is enough evidence for Holmes to stand trial.