A preliminary hearing started today for James Holmes, the 25-year-old former graduate student charged with killing 12 and wounding 58 people last July during a screening of “Batman” at a Colorado movie theater. During the hearing, which is expected to last one week, prosecutors must convince the judge they have sufficient evidence to put Holmes on trial.

Up until now many of the facts surrounding the shooting were suppressed under a court-imposed gag order, so the hearing may give the public new insight into the horrific event and a glimpse of both the prosecution and defense’s cases. It is anticipated Holme’s lawyers will file an insanity plea, and their plan to call witnesses to testify about Holme’s state of mind further supports this assumption. Also, leading up to the hearing, defense lawyers commented that Holmes was mentally disturbed and had seen a psychiatrist.