CENTENNIAL, Colo. — The officers struggled to hold back the tears as they recalled the Colorado theater shooting: discovering a 6-year-old girl without a pulse, trying to keep a wounded man from jumping out of a moving police car to go back for his 7-year-old daughter, screaming at a gunshot victim not to die.

“After I saw what I saw in the theater — horrific — I didn’t want anyone else to die,” said Officer Justin Grizzle, who ferried the wounded to the hospital.

A bearded, disheveled James Holmes, the man accused of going on the deadly rampage, didn’t appear to show any emotion as Grizzle and the other officers testified Monday in a packed courtroom as survivors and families of those who died watched quietly. At one point, a woman buried her head in her hands when an officer recalled finding the 6-year-old girl.

“He’s heartless. He really is. He has no emotion. He has no feeling. I don’t know anybody can live that way,” Sam Soudani said of the gunman afterward. His 23-year-old daughter survived after being hit by shrapnel from an explosive device at the theater.

On the first day of a hearing that will determine whether there’s enough evidence to put Holmes on trial, the testimony brought back the raw emotions from the days following the July 20 attack at the suburban Denver theater that left 12 people dead and dozens wounded.

The massacre thrust the problems of gun violence and mental illness into the forefront before they receded in the ensuing months. Now, just weeks after a shooting spree at a Newtown, Conn., elementary school left 20 children and six adults dead, prosecutors are laying out their case with the nation embroiled in a debate over gun violence and mental illness.

Any new details to emerge this week — including Holmes’ mental state — will come amid the discussion over an array of proposals, including tougher gun laws, better psychiatric care and the arming of teachers.

The hearing is the first extensive public disclosure of the evidence against Holmes. Other information has come out, including details about how he legally bought his guns in person and purchased thousands of bullets and body armor online as well as a notebook that he sent to a psychiatrist he had seen.

A district judge forbade attorneys and investigators from discussing the case publicly, and many court documents have been under seal.

It took this long to get to the preliminary hearing because lawyers have been debating what physical evidence should be made available to one side or the other, whether the psychiatrist who met with Holmes is barred from testifying by doctor-patient privilege and who was responsible for media leaks.

It wasn’t immediately clear whether the doctor would testify this week.

On Monday, prosecutors called on the first responders to testify about the shooting at the midnight showing of the latest Batman movie, “The Dark Knight Rises,” in Aurora. Holmes had bought his ticket almost two weeks in advance. Investigators say Holmes, wearing body armor, tossed two gas canisters into the packed theater and then opened fire.

When officers arrived, they saw people running out of the theater and trying to drive away. Others walked. Some of the wounded tried to crawl out.

Officers found Holmes standing next to his car. At first, Officer Jason Oviatt said, he thought Holmes was a policeman because of how he was dressed but then realized he was just standing there and not rushing toward the theater.

Oviatt pointed his gun at him, handcuffed him and searched him. He said he found two knives and a semi-automatic handgun on top of Holmes’ car. An ammunition clip fell out of his pocket and Oviatt found another on the ground. He said Holmes was dripping in sweat and his pupils were wide open.

Prosecutors did not indicate why Holmes’ pupils were dilated.

Oviatt said Holmes seemed “very, very relaxed” and didn’t seem to have “normal emotional reactions” to things. “He seemed very detached,” he said.

Holmes volunteered that his apartment had been booby trapped, the officers said.

At one point, Grizzle asked Holmes if anyone had been helping him or working with him. “He just looked at me and smiled ... like a smirk,” Grizzle recalled.

Officer Aaron Blue said Holmes was fidgeting around after he and Oviatt put him in a patrol car, prompting them to stop and search Holmes again. They were worried they might have missed something because of Holmes’ bulky outfit.

Inside the theater, the movie was still playing on the screen. An alarm was going off and moviegoers’ cellphones rang unanswered. There was so much blood on the floor, Grizzle said, that he slipped and almost fell down.

Blue went with Jessica Ghawi, who was shot in the head, to the hospital. He said he held the head of the 24-year-old aspiring sportscaster steady in the backseat while someone else drove so she could keep breathing. She later died.

Caleb Medley was also wounded in the head, and Grizzle recalled the 23-year-old aspiring comedian struggling to breathe on the way to the hospital. Every time he thought Medley had stopped breathing, Grizzle said, he yelled at the man not to die. Medley survived, and his wife gave birth to their first baby days after the shooting.

Another man Grizzle took to the hospital kept asking where his 7-year-old daughter was. For about half of the trip, Grizzle said, he had to restrain him from jumping from the patrol car. At one point, the man opened the door and tried.

Sgt. Gerald Jonsgaard recalled not finding a pulse on the youngest victim, 6-year-old, Veronica Moser-Sullivan. In talking about not finding a pulse on her, Jonsgaard had to stop talking because he was about to break down in tears.

Two pathologists testified that the victims who died were shot anywhere from one to nine times. Matthew McQuinn, 27, who dived in front of his girlfriend to shield her from the bullets, was shot nine times.

Holmes, now 25, is charged with more than 160 counts, including murder and attempted murder. The hearing will allow the judge to determine whether the prosecution’s case is strong enough to warrant a trial, but it’s rare for a judge not to order a trial if a case gets this far.

Legal analysts say that evidence appears to be so strong that Holmes may well accept a plea agreement before trial.

While prosecutors have yet to decide on whether they will seek the death penalty, such a plea could get Holmes a lesser sentence, such as life in prison; help the state avoid a costly trial; and spare survivors and families of those who died from the trauma of going through a lengthy trial.