[Leaning Right]

He SHOULD have had the gun not knowing where the criminal was. The police SHOULD have announced their presence in no uncertain terms HANDS UP. and then the homeowner SHOULD have reached for the sky.

All good points. But here's is something I wonder about. Suppose a bad guy with a gun is told "Drop the gun. Hands up!" The bad guy thinks "I better do that or I might get shot."

But suppose it's a good guy with a gun. He's more likely to think "Huh? What? Wait...I'm not the bad guy here...". He might even get confused, and pivot towards the sound of the command. Then he gets shot.

As you said, a cluster fudge.

[Gaffer]

If he is INSIDE your garage and has a gun, shoot him. You then tell your story, let his corpse tell its side.

[Vaquero]

I would throw my hands up (as the homeowner). Plenty of time to straighten it out.

Of course if the perp is still in the nearby picture, the part where it is straightened out should be done with some expedience