The school computation book has been one of the most important and closely guarded pieces of evidence in Holmes' death penalty trial, yet its contents only widened the diverging views of the man responsible for one of the worst mass shootings in U.S. history. To prosecutors, it's the diary of a methodical killer, complete with detailed maps and drawings of auditoriums in the suburban Denver movie theater and the merits of each as the scene of mass murder. While prosecutors honed in on portions of the journal where Holmes describes his plans for mass violence, defense attorneys focused on nonsensical scribbles and odd symbols and the word "Why?" repeated over several pages.