In that case, if the guy deserved to die, or would benefit the world from his death, then yes, I'd shoot him whether or not I was being threatened. And I'd possibly torture him a little first.
And no, I'm not just trying to be 'edgy' (screw you Tim Langdell!) by saying that. I am being serious. I do actually have a little urge inside me to want to hurt someone, to take pleasure in their pain and to want to torture them. Of course, I would never do this in real life, but there is that basic desire. Personally, I think all humans have that same desire, as it's just an urge to gain power and control which is a very human and natural thing to feel. It's just that societal conventions mean that anyone who acts on those urges and impulses is cast out and branded a criminal or a psychotic maniac.
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What the hell am I doing on a Maths course at uni? I should have done Psychology, I'm much more interested in this stuff than Differential Geometry...
Anyway, I just act out these urges by writing about them anyway, or imagining them. The last short story I came up with (yet to be written) had a character who, aside from having an incestuous love for her brother, loved to torture and kill people (and she was one of the good guys!). So, she ends up capturing an enemy agent (it makes sense in context), and torturing him for information while getting very turned on, then just spending a whole night torturing him (and killing him the next morning as they both orgasm... yeah, it does happen in the story...).
I'm a crazed loon, aren't I?