In his original statement, he said he thought it was a gun; That "thought" isn't a profession of doubt, but rather a profession of his inability to provide evidence. "I thought I saw a gun" only covers you for shooting at an unarmed man if you are certain that you thought you saw a gun.
So later saying that you were never certain there was a gun means you were NEVER certain you were in danger, and in the absense of clear indication of danger, you aren't supposed to shoot. YOu don't get to shoot people because you think they might be threatening you, you have to have a reasonable certainty that you are in danger.
Coupled with the absense of a single person at the scene who heard the two ever say anything about there being a weapon in the hands of a suspect that was on the loose, it is rational to believe that "I thought he had a gun" was the statement of a man trying to justify why he took shots at a fleeing man, and not a statement of a certainty of fear of danger.
And since Compean says that he no longer felt in any danger when Ramos showed up and shot the guy, it's bad for Ramos as well to claim he saw a gun and felt threatened. So much so that Ramos testified that Compean was laying on the ground, when Compean claimed first that he was standing, and later that he was kneeling, but NEVER that he was laying down.
No, Chucky... See page 62. His first statement was: