Nearly one year ago, James Holmes entered a Century movie theater in Aurora, Colorado with tear gas and guns, killing 12 people and injuring over 60 others. The shooting took place during an opening weekend showing of The Dark Knight Rises, turning crowded summer movie blockbuster premieres into yet another place where Americans are now wary of guns (though at least one Missouri movie theater recently forgot this).

Now, Holmes’ murder trial is about to begin, and prosecutors seem to have an incredible amount of evidence to demonstrate that he was the shooter. According to an Associated Press report, prosecutors this week filed a motion in court that states they have close to 3,500 potential witnesses that could be called on to testify. In addition, prosecutors estimated they have almost 40,000 pages of evidence that have been filed.

Holmes will be tried on multiple counts of first-degree murder. Prosecutors have turned down a plea offer from Holmes’ defense for the suspect to plead guilty if they agree not to seek the death penalty, stating they do intend to seek the death penalty. Holmes’ lawyer recently requested the suspect’s plea be changed to not guilty by reason of insanity, which the judge in the case is currently deciding whether or not to accept.