If the person is in their right mind, it' a classic case of double effect. Sometimes one act has two effects, only one of which is intended, while the other is not intended either as a means or as an end. And intention is very important in the moral evaluation of acts.
So if the person acts to avoid terror and agony (survival being entirely out of their hands) -- that is a moral choice.
Or, on the other hand, if the person is NOT in their right mind, but is jumping out of the window in sheer adrenalin-forced terror, that also is not an immoral act because the person is not responsible for their act.
With me so far?
In the case of the dying officer --- in my judgment --- the intention could have been not to destroy his life, even as a means to an end, but purely to destroy the sensation of pain.
If, per impossible, he had managed to shoot out the pain receptors in his brain, without killing himself, it would have been enough, he would have been (in his horrible circumstances) satisfied wth that. In my judgment, his direct intention was to destroy the sensation of pain, and he had good reason to believe that his death was, in any case, imminent --- that part of it was not under his control. Therefore, it was a morally defensible act.
That's as well as I can reason it out.
God understands every detail of the situation, and will render a verdict so absolutely right that on the Last Day we will all be cheering and punching the air and saying, "God Almighty! Your mercy is triumphant and Your judgment is perfect."
Wonderful explanation!
Now how does it apply to the original situation of the discussion: if I have an inoperable brain tumor, I am going to die and Im in a constant, intolerable state of pain, how many days before my death is it ok for me to kill myself without sinning?
When can someone put poison in my I.V. at my beckoning and not be a murderer?
Or is it always wrong, in the case of a terminal disease? Even 30-seconds before your natural death?
Sorry to be late to respond to P.B... but I think your response Mrs. D is excellent... I have nothing to add.