Dead bodies and blood covered the floor inside the Aurora, Colorado, movie theater after a gunman opened fire on scores of people last summer, killing 12 and wounding 58, according to Aurora police officer Justin Grizzle.

Grizzle, who testified Monday about the horrific scene he witnessed on July 20, was one of the first responders to enter the theater after the shooting. The 13-year police veteran testified during the first day of James Holmes' preliminary hearing that will determine if there’s enough evidence against Holmes to send his case to trial.

As he was fighting back tears, Grizzle said he helped rush badly wounded victims to a nearby hospital in his police cruiser, including shooting victim Ashley Moser and her husband, who wanted Grizzle to turn around and head back to the theater.

"He was shot in the head somewhere. He kept asking where his ... daughter was," Grizzle said. "He opened the door and tried to jump out."

Read more: How the Aurora survivors are doing

Grizzle said he drove and held the man by his shoulder to keep him in the car. The man’s daughter was 6-year-old Veronica Moser-Sullivan, who was killed in the shooting at a midnight premiere of the new Batman movie, "The Dark Knight Rises."

Veronica's mother, Ashley, was paralyzed in her lower half and miscarried after the shooting.

Holmes did not speak and did not show any emotion during Monday’s testimony. Family members of the victims in attendance Monday sobbed at some points and held each other for support.

Holmes is facing more than 150 criminal charges, including 24 counts of first-degree murder. Holmes has not entered a plea.

If Holmes' case goes to trial, his attorneys are expected to argue that their client has "diminished capacity," a term that the Colorado Bar Association relates to a person's ability or inability "to make adequately considered decisions" regarding his or her legal representation because of "mental impairment or for some other reason."