I clearly remember that the first wound to Sheila being said by Knight (I think it was) as not causing immediate incapacitation. There could be suggestions there may not necessarily have been blow back from the second wound but it escapes me now if it were possible or not though. From memory I believe an artery was was clipped. If anyone has access to that report it's a must read.
Here's the thing though: let's suppose for one moment that Sheila Caffell shot herself (last in the order of events, obviously) after having murdered everyone else.
Now, if she shot herself, then (as we all know) she must necessarily have shot herself without the sound modifier (silencer) on the rifle, for two reasons: firstly, the modifier was not attached to the rifle as it lay across her body; and secondly, she couldn't have reached the trigger if the rifle had had the modifier attached.
So we know that - in the "Sheila did it" scenario - that she shot herself with no modifier on the rifle.
But....
Even with no modifier attached, she could only just have managed to reach the trigger with her hand, given the position of the two entry wounds.
Which means that the end of the rifle's barrel would have been either pressed hard up against her chin when the shots were fired, or only a matter of a couple of cm away.
Yet.... zero evidence of powder burns or tattooing were found anywhere around her entry wounds. And that would be inconceivable from such a close-up shot from a .22 rifle with no modifier attached.
Oh, and we also have the (inconvenient, for Jeremy) trial evidence that there was no powder residue anywhere on Sheila's hands, arms or nightdress: extremely unlikely at best, impossible at worst, for someone who'd just fired numerous rounds from a breech-loading rifle, reloading midway through.
Oh and we have the further (inconvenient, for Jeremy) trial evidence from the pathologist that the blood flow patterns on Caffell were not consistent with her lying face up when the shots were fired, but rather that she was very probably in a seated or semi-seated position when the shots were fired.
No dice on the "Sheila did it" front, I'm afraid. And given that she was the only other conceivable suspect, that leaves just one person.......