Is there any reasonable doubt that the officer abused his power? The officer shot a man with witnesses. There's no doubt that the officer killed an innocent man

Is there any reasonable doubt that the officer abused his power? The officer shot a man with witnesses. There's no doubt that the officer killed an innocent man. The facts have been established that the officer had no cause to use that amount of force. That being the case, what reason is there to not put the officer in prison awaiting trial like any other person that committed murder?