Prosecutors have identified approximately 3,500 witnesses in the Aurora movie theater shooting case, according to a new court document filed by attorneys for accused murderer James Holmes.

Public defenders for Holmes told a judge today that they need more time reviewing an 83 page document compiled by prosecutors that lists the potential witnesses. The deadline for finishing the review was supposed to be May 17, but Holmes' legal team says it needs a 45 day extension.

"The additional time required is not only because of the sheer volume of witnesses endorsed by the prosecution, but because counsel have been working diligently on other important and necessary matters," Holmes' attorneys said.

Holmes is accused of opening fire last July 20 during a midnight screening of "The Dark Knight Rises" Batman movie, killing 12 people and injuring another 70. He faces a total of 166 counts, including murder and attempted murder.

Through his attorneys, Holmes told a judge Monday that he wants to change his plea to "not guilty by reason of insanity." A judge had earlier entered a plea of "not guilty" on Holmes' behalf. During a hearing Monday, Judge Carlos Samour signaled he would allow the plea change but won't make an official decision until the end of the month.