Clues exist which can be relied upon to distinguish which of the two shots had been fired, one before the other..
First of all, (1) death would have occurred instaneously once bullet PV/20 had been received, whereas, (2) Sheila could have survived and moved around for a while, until PV/19 was recieved..
Secondly, Sheila's body had been the body of a woman seen through a ground floor laundry room window, prior to the firearm officers entering the premises. Thirdly, Sheila had been the female body reported as dead inside the kitchen, as mentioned in timed police message log entries (7.35am, 7.37am, 7.38am, 7.42am, and 7.45am), and Sheila was none of the three bodies found upstairs by 8.10am - from this information we can successfully conclude that the very first shot inflicted to Sheila's neck must have been, and could only have been bullet PV/20 ( the piece of a badly fragment bullet...