Witnesses and survivors of the Aurora, Colo., movie theater slaughter looked on Monday as police officers gave graphic testimony at a pretrial hearing for defendant James Holmes.

Holmes is accused of killing 12 people and wounding roughly 70 more during a midnight screening of “The Dark Knight Rises” on July 20, 2012.   

Monday’s proceedings were just the first day of the hearings to determine if there is sufficient evidence to place Holmes on trial. The 25-year-old former neuroscience student is charged with 166 counts of first-degree murder and attempted murder along with possession of explosive devices. He  has not yet entered a plea but is expected to plead not guilty by reason of insanity.

This was the first time police and witnesses have spoken publicly on the bloodbath since Arapahoe County District Judge William Sylvester enacted a gag order days after the shooting. Only radio transmissions have been made public in the six months since the crime.

CBS reported that the district attorney wrote a letter to the still-grieving families warning them that the testimony may be too much for them to hear and requested they “carefully consider whether or not you think that you are ready to be exposed to potentially difficult information at the hearing.”

Perhaps the most disturbing details to come out of the hearing came from first responders. Aurora Police Detective Matthew Ingui said the scene was “heartbreaking,” and that victims “were crying. Some of them were covered in blood, missing shoes.”

“He was very relaxed,” said Officer Jason Oviatt, who testified he discovered Holmes behind the theater standing near his car with a gun nearby, according to the Denver Post. “It was like there weren’t normal emotional responses,” and that Holmes was “not doing anything. Not in any hurry. Not excited. Not urgent about anything.”

Police found an assault rifle by the car door, a gun case in Holmes’ car, a knife at his belt and magazines stuffed into his pockets. Oviatt said Holmes first appeared to be a police officer because he was wearing so much body armor.

Other police men said that while the body search was taking place behind the movie theater they were trying to help the victims, who were lying in the parking lot and screaming in pain.

“I slipped. I almost fell down because of all the blood there,” said Officer James Grizzle, who drove six victims to the hospital. “There was so much blood I could hear it sloshing in the back of my car.”

Holmes was sporting a dyed orange afro when he was arrested, an apparent attempt to channel Batman villain The Joker, according to what he told police in July. Multiple sources described Holmes as "zombie-faced" and wearing his brown hair long with a thick beard during Monday's hearing.

The judge will decide at the end of the week if there is enough evidence implicating Holmes, something that appears to be a virtual certainty even with the news that the defense team will call at least one mental health expert to the stand on Holmes’ behalf. Prosecutors have not announced whether they will pursue the death penalty in the case, saying they’ll first consult with families of the victims.