DENVER - A man accused in the June shooting death of a Denver police officer at an outdoor concert will go to trial, a judge decided Thursday.

Rollin Oliver, 21, is charged with first-degree murder with extreme indifference in the June 24 slaying of Officer Celena Hollis.

The shooting happened on a Sunday night in front of hundreds of people who had been attending a jazz concert at City Park. Officer Hollis was trying to break up a fight when she was shot in the head, police said.

During Thursday's preliminary hearing, defense attorneys said Oliver had brought a handgun to the park for self protection. They said Oliver had been shot before and had to undergo several surgeries and learn how to walk again.

Defense attorneys argued Oliver fired the gun in self-defense as he tried to flee gang members who were beating up his friend.

Prosecutors, however, said Oliver was holding the gun with both hands as he fired indiscriminately into the crowd.

Denver homicide Detective Jaime Castro testified that Oliver admitted during questioning that he knew he could hit someone by firing into the crowded park.

Castro also testified that four bullet casings recovered at the scene matched the gun found in Oliver's waistband when he was arrested.

The detective also said that a bullet fragment recovered at the scene contained some of the slain officer's DNA and also matched the other bullets fired from Oliver's gun. Another bullet was found buried in the ground.

Defense attorneys argued that Oliver should face trial on lesser charges, saying there was no premeditation and he didn’t intend to kill anyone.

But the judge said the trajectory of the bullets, one hitting the ground and another hitting high on the wall of the park pavilion building, indicated that Oliver was indiscriminately shooting into a crowd and this warranted a trial on first-degree murder.