Almost six months after 12 people were killed and at least 70 were injured in a shooting rampage at a movie theater in Aurora, Colo.—and just days after a deadly hostage standoff rattled the town once more—the highly anticipated preliminary hearing is set to begin today for accused mass shooter James E. Holmes.

The purpose of the preliminary hearing, which is expected to last through the week and draw hundreds of witnesses, victims, and members of the media to the Arapahoe County courthouse, is to determine if there is sufficient evidence to put the 25-year-old former University of Colorado Denver neuroscience doctoral student on trial.

Holmes, who has not yet entered a plea and has made at least one suicide attempt by running headfirst into a jail cell wall, has been charged with 166 counts of first-degree murder and attempted murder and possession of explosive devices.

This will be the first time that details about the shooting and Holmes’s capture by police minutes after the rampage will be revealed. In July, Arapahoe County District Judge William Sylvester issued a gag order barring attorneys and investigators from speaking publicly about the case.

The contents of a notebook that Holmes sent his school psychiatrist, Dr. Lynne Fenton, on July 19—the day before the shooting—that reportedly contained violent images of an attack may also be divulged.

Holmes is suspected of gunning down 12 people and injuring 70 others in a shooting spree at the midnight showing of The Dark Knight Rises at the Century 16 movie theater on July 20 in Aurora. On that fateful night, police say Holmes, with his hair dyed red as a creepy homage to Batman’s Joker, was dressed in combat gear and armed with an assault rifle, a Glock pistol, a shotgun, and two canisters of what sources say was tear gas.

After Holmes was arrested at the back of the theater, police discovered that his third-floor apartment had been booby-trapped with explosives, trip wire, and gasoline. Authorities believe that Holmes had rigged his apartment so that it would kill responders when they arrived to investigate after the shooting.

Police say Holmes went on his rampage one month after he withdrew from the Ph.D. program after failing a year-end exam. On that day, he bought an AR-15 semiautomatic rifle to add to his burgeoning collection of weapons.

At the preliminary hearing, Arapahoe County prosecutors will likely outline their case against Holmes and present evidence to show that Holmes’s rampage was premeditated and that he methodically began preparing for the attack months earlier. In an earlier hearing, prosecutors said that in March of 2012 Holmes told a fellow classmate he wanted to kill people.

Prosecutors are also expected to call to the stand police investigators, first responders, coroner officials, as well as a number of injured moviegoers who witnessed the bloodbath. In addition, prosecutors are set to play the 911 calls by dozens of frantic moviegoers as well as show some of the 30 hours of video from the theater.

Holmes’s defense team, which has repeatedly suggested that the wiry former student suffers from mental illness, is planning to call at least one mental-health expert, and will undoubtedly take the position that Holmes, who now sports longer brown hair and a bushy beard as he sits zombielike through hearings, was insane at the time of the mass shooting and can’t be found guilty of the heinous crimes.

According to ABC News, defense attorneys also plan to call two unidentified witnesses who will testify about Holmes’ mental state—a move that was heavily opposed by the prosecution at a hearing last week. The witnesses, who have never been interviewed by the defense team, are cooperating with Colorado law-enforcement authorities, ABC reported.

The preliminary hearing will be held in the courthouse’s biggest courtroom, and there will also be overflow rooms capable of seating hundreds of people. Armed law-enforcement personnel will be stationed on the court’s rooftops. The hearing is expected to draw hundreds of spectators, including the macabre fans of Holmes who call themselves Holmsies.

Meanwhile, the theater, which has been closed since the shooting, is set to reopen on Jan. 17. Several family members of those killed have criticized Cinemark, the theater owners, after they sent them invitations to the grand opening offering “a special evening of remembrance” followed by the showing of a movie.

In a letter to Cinemark, the families wrote: “During the holiday we didn’t think anyone or anything could make our grief worse but you, Cinemark, have managed to do just that by sending us an invitation two days after Christmas inviting us to attend the re-opening of your theater in Aurora where our loved ones were massacred.”