DENVER (CBS4)- The man accused of shooting and killing a Denver police officer after a jazz concert in City Park said he’s not guilty.

Rollin Oliver entered the not guilty plea during a court hearing on Thursday.

Oliver, 21, has been in jail since his arrest and wants to be released on bond. A decision from the judge on bond won’t come until November.

Oliver is charged with first degree murder with extreme indifference in the fatal shooting, which took place at City Park during a Jazz in the Park concert in June.

Celena Hollis, a Denver police officer, was shot in the head and killed while reportedly trying to break up a fight between rival gang members.

During pre-trial testimony in September, no one on either side of the case denied that Oliver fired the fatal shot, and one detective who took the stand related a number of witness statements and evidence, including:

Officer Celena Hollis (credit: Denver Police)

- A 40 caliber handgun was found tucked into Oliver’s waistband when he was arrested near the scene.
- Four bullets — including the one that killed Hollis — were fired from Oliver’s gun.
- Oliver admitted to firing at least two shots.

During that testimony, a line of questions from the defense revealed that Oliver had the gun for protection after being shot once in the past. William Drexler, Oliver’s defender, tried to weaken reported ties to a gang and claimed that Oliver fired the gun as he was running from the scene and chased by a group of gang members that were violently assaulting his friend.

Drexler said Oliver purchased the gun after he was shot at an unrelated party and they say this is a case of self defense.