Prosecutors in the Colorado theater shooting trial have worked to paint a powerful image of grief and gore that experts say could be hard for defense attorneys to overcome.

They've already called more than two dozen witnesses, each with tragic stories of what happened in the suburban Denver movie theater where James Holmes killed 12 people and injured 70 more. Half-empty tissue boxes littered the floor of the courtroom after a day of dramatic testimony.

Joseph Rice, a managing partner of the Jury Research Institute, says it's almost impossible for jurors to ignore so much emotion.

He says defense attorneys should give jurors the tools to focus on the issues in the case.

Jurors must decide whether Holmes was legally insane at the time of the July 2012 attack.