James Holmes and his defense attorney Daniel King sit in court for an advisement hearing at the Arapahoe County Justice Center in Centennial, Colorado, June 4, 2013. Reuters

James Holmes was found guilty Thursday on 12 counts of murder for the shooting deaths of 12 people inside a movie theater in Aurora, Colorado. Holmes now heads to sentencing where he could face the death penalty.

The jury began deliberating on Wednesday, after the prosecution brought its final witness to the stand: a victim who had survived the shooting but had lost her pregnancy and small daughter that night. Prosecutors are pushing for the death penalty, and had rejected Holmes' not guilty by reason of insanity defense, saying that the attack was premeditated and meticulously planned.

Moviegoers that night had come to the theater for the premiere of the the latest installment of the Batman franchise, "The Dark Knight Rises," District Attorney George Brauchler said during the trial, breaking down with emotion. “But that's not what happened. Instead, a different figure appeared by the screen dressed all in black, and he came there with one thing in his heart and in his mind, and that was mass murder."

Holmes did not testify during the trial, which lasted 40 days.

Century Aurora 16 movie theateris pictured in Colorado April 27, 2015. Reuters

A total of five jurors were dismissed for failing to follow court rules regarding media through the trial. The prosecution called 226 witnesses to the stand, and the defense brought in 30.

The decision comes four days shy of the third anniversary of the attack, in which Holmes showed up at a midnight showing of the newly released and highly anticipated "The Dark Knight Rises" and killed 12 people while walking up and down the aisles. Surviving victims said at the time said that a noxious gas was used just before Holmes started shooting. While Holmes reloaded, survivors said they were forced to decide whether or not to stay in the theater and help the wounded. Those who left the theater recalled running past bodies in the aisles.

Holmes had four firearms on him: an assault rifle, a shotgun and two handguns. In addition to the 12 fatalities, 70 people were injured in the attack that began about 20 minutes into the movie. The youngest victim was 3 years old, and the fatalities ranged from ages 6 to 32.

Victims and family of victims wearing Batman clothes arrive for the second court appearance of James Holmes, in Centennial, Colorado July 30, 2012. Reuters

The attack was the deadliest shooting in Colorado since the 1999 Columbine High School attacks.