"Honestly believe". I mean what does that even mean.
It means a belief that is genuinely and reasonably held. If a belief is unreasonable in the situation, it is not an honest belief.
"It does not matter, if that is mistaken". It matters to Me. On principle. It would matter to me if it was my son. If my son was killed.
I understand where you are coming from, but that is the standard in law.
Imagine you are an armed police officer called in to a hostage situation. The hostage taker has a gun, is pointing it at one of the hostages and threatening to shoot them. You would reasonably believe that the hostage's life is in danger, so could shoot the hostage taker. If it subsequently turns out that the gun was a replica or did not have any ammunition, your belief would have been mistaken. Does that mean you are now a murderer because you shot the hostage taker? If it does, you could never shoot a hostage taker in this situation because you could never be certain that the gun was real and was loaded.
This applies to everyone, not just police officers. Imagine you are a hostage. The hostage taker has a gun, is pointing it at one of the hostages and threatening to shoot them. You find an iron bar and hit the hostage taker over the head with it, killing him. Even if it turns out that the gun was a replica or did not have any ammunition, you are not guilty of murder because you genuinely and reasonably believed that the hostage taker was about to kill someone, even though that belief was mistaken.
To get a conviction, they need to prove ... no. That burden of proof is too far fetched, too far in the other direction, for my liking. It's too extremist. They should only need to prove ..... I'm not sure what, but something less.
Not far-fetched at all. That is simply what is required to prove guilt beyond reasonable doubt. Are you suggesting a lower standard of proof for convictions? If so, for everyone or just for police officers?
So there's a previous crime, admittedly. And the police then think that this person is a notorious killer. And they're chasing him. And he's shot. In the head. Not in the leg to stop him eg running off. But in the head. Not the shoulder.
Hollywood has a lot to answer for. In a stressful situation with a hand held gun, even if it has an accurate laser sight, it is difficult to hit someone as precisely as you think. You may be able to get shots within a 6 inch circle at 30 yards in training, but that doesn't mean you can do it in a live situation. For that reason, police are generally trained to aim for the middle of the torso. That gives them the maximum chance of hitting the person they are targeting, and minimises the chances of them missing and accidentally hitting someone else. Of course, if you are shooting at someone sitting in a car, you may only be able to aim at their upper torso and head unless you are very close to the car.
"I thought one or more of my colleagues was about to die."
If I was defending him, I could give a number of explanations as to how he might have reasonably thought this. However, I am not expressing any view on his guilt or innocence.
You clearly don't accept that he reasonably believed that anyone was about to die. If the jury agree with you, the prosecution will have met the burden of proof you described as "far-fetched". They will have shown that he did not honestly believe that opening fire was necessary to protect anyone but he chose to use deadly force anyway.
Of course there will be no prosecution
There may be no conviction but there is clearly a prosecution.