Isn't it really as simple as this, if you truly believe they intended to murder this man in cold blood for no reason, they knew it wasn't him and blew him away because of his colour, because he said something rude or they just wanted to kill someone fine, they should go to jail.
If at the end of the day you believe that it was a horrific accident but in reality they had no malice or intent to hurt an innocent man but truly believed they were doing the right thing and trying to save lives then how you can want them to be done for unlawful killing I don't know.
The premeditated or reactionary murder of someone for no reason and in no way trying to help anyone and without real reason should be punished in society. Punishing those that made an honest to god mistake, no matter how severe the consequences of said mistake is just being petty.
In war time you don't punish or jail a soldier who in the middle of a fire fight with people shooting at him, a kid runs out of a building into the line of fire and gets shot. You could call it murder, the bullet came from the soldiers gun, he did kill the child, and while its the mother of all consequences the action wasn't immoral or unjustified when it took place, just the result. You can't base your opinion on the result but the action as it was taken and the reason it was taken, which in this case in know way appears "wrong".
Now the fact is they are probably all decent men, all people who will live with the guilt and trauma of such an event for life as it is, the idea of putting them in jail for trying to do the right thing is ridiculous.
If you look just at the result and not at the reason, then take a case of a woman killing a man who was beating her and thought he would kill her. reasonable person would deem this self defence and justified, if you ignore the reasoning and simply look at the fact that he's dead and she's not you'd send her to jail. Someone dying doesn't automatically mean someone should be put in jail to rot for life.
if someone can come up with a reason as to why they killed him other than trying to do the right thing, in this case they'd been led to believe, however wrongly or badly it was communicated, that this man could well be about to kill dozens/hundreds of people and in that second you decide to shoot and hopefully save them all, or wait 5 seconds see yourself aswell as hundreds die in a bomb.
Its a tragic accident, but it wasn't random, and if you can't see that eventually innocent people get caught in the crossfire then you're blind, its tragic, but it was inevitably going to happen sometime, and will happen again. If you want no protection and no risk of police accidentally catching mistaking you, live in a country without a police force, of course your risk of dying in a violent crime is massively increased that way. This is life, its not perfect, its not perfectly safe, never has been and never will be.
