What do you mean "by all accounts" Mike?
Not by any account I've ever read - other than yours, of course 
The evidential account I refer to, involves the images of Sheila on the bed with a solitary wound on her neck, and the other images of Sheila on the bedroom floor with two wounds and fresh blood running and leaking from the wounds, and corners of her mouth, etc...
Now...
in the first image I refer to, there was a small dried and fading blood trail which ran vertically, but no other bloodstains or wounds at all on her neck. What seems apparent to me is that because there was no blood at all running from the lower wound at the time Craig and Miller saw Sheila in the bedroom at 8:44am, Craig made the mistake of thinking that Sheila had in fact died, but she had not died at all by that stage. She did not die until after the second shot was inflicted, and because Sheila had been taking drugs the blood which poured out of the upper wound and the sides of her mouth appeared to be diluted (thinned). Nevertheless, what becomes clear is that Sheila's heart was still beating by the time the second shot was inflicted...
All Craig and Miller had to go on at 8:44am, was a solitary entry wound with a vertically dried, fading blood trail, on Sheila's neck, which caused Craig to make the terrible mistake of pronouncing Sheila as being dead, at 8:44am. However, if Craig had been present inside the bedroom when the second shot was accidentally fired or discharged, Craig would have then realized that Sheila's heart was still beating because blood was being pumped out of the body, in particular out of the second entry wound...