TexasCHLforum.com

Per the Chronicle story, apparently the officer had been drinking

Hoffman also said that while Coronado had been drinking, he was not intoxicated. He noted that HPD officers are not allowed to take police action if they have a measurable amount of alcohol in their system, but that his client was in a difficult position

So, the question will come up in the investigation if he was administered a breathalyser or not. While it sounds like this was a justifiable shooting by the accounts, he may still have to clear the question of how much alcohol he had in his system since he engaged the BG's.