I think this is quite well-reasoned. I can think of a few objections.
The neighbours insisted it was a terrible sound, someone only makes when about to die.
This is easy for them to say in retrospect, when they know that she
did die.
Can you think of anything inside a locked bathroom that would cause this
In a South African bathroom? An enormous cockroach.
Finally, I can't think of anyone, having heard their wife scream, then shooting at the bathroom door, knowing she was in there.
Well, it is possible for people to behave really stupidly under stress. I read Dawkins' autobiography a while back. He tells the story of a relative who was out riding his bicycle during WWII when a bomb fell, and, thinking his house (with his wife in it) had been bombed, threw his bicycle in a ditch and
ran home.
f it was a burglar, because she was locked in and we know there was no burglar with her, because of the TIMING, because the shots soon came after the scream
This, on the other hand, is a point you could have made more of. If the noises came in short sequence, then to suppose Pistorius innocent we have to suppose that he was already carrying his gun around, or was anyway sitting next to it, when he heard his wife scream. Why?
On the other hand, we have to wonder why he called for help. It would have taken
exceptionally quick thinking on his part to think: "I'm about to kill my wife in a murderous rage, how can I excuse this when questioned?" Or, alternatively, if it was carefully premeditated, then how could he arrange for her to lock herself in the bathroom?
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I haven't read anything about this case myself, I'm just going by what you've told me.