DENVER -- It's an emotional and controversial case that has gone on for nearly three years.

Now, the Denver police officer who has been at the center of the storm is talking publicly for the first time.

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7NEWS Reporter Julie Hayden spoke with Denver Police Sgt. Dan O'Shea (pictured, left) after he watched exclusive 7NEWS videotape from the day of the Columbine High School massacre.

O'Shea has now told El Paso county investigators his version of what happened that day. And he said the 7NEWS tapes, which he had never seen before, support that story.

He also said they prove that he did not shoot Danny Rohrbough, as Rohrbough's parents claim.

O'Shea said AirTracker7 captured all four occasions when he fired shots at Columbine.

The first time, he said he returned fire at Harris and Klebold, who were shooting at ambulance crews trying to rescue students.

He said, and other witnesses agree, that Danny Rohrbough was already dead.

Later, he said he fired three times to provide cover as other officers checked Danny's body.

The Rohrboughs claim the three shell casings found there prove he killed Danny, but O'Shea said the videotape proves he did not kill anyone.

O'Shea said he is hurt and offended by the accusations that he killed Danny Rohrbough.