OK so lets assume the diagram, as posted by Kaldin, is a true and accurate representation of where the cases lay on the morning of the shootings (bar the case on the stairs).
Having viewed the pictures of where Sheila lay and the pattern of bleeding from both the wounds in her neck it appears to me the two shots occurred within a short time of each other (a couple / few seconds). This is because there is a common pattern in the flow of blood which would be influenced by gravity.
Is if a fair interpretation that both wounds occurred within a short period of time?
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I beg to differ about blood running and leaking from both wounds - I think there was blood leaking from only one of the wounds, and that as a result of Sheila's body, and head being repositioned, the upper wound came to rest upon the lower wound, and blood which is shown, or which appears to be running from the lower entry wound, is in fact blood that was running and leaking from the upper wound, before the position of the victims head was adjusted into a different position...
If you look close enough, you can see that there is no vblood running from the lower wound at all, only the upper wound...
Blood from the lower wound, ran in a completely different direction - which you can see if you care to take the time and trouble to notice...
In my opinion...