I believe Sheila shot herself. Then when police broke in the police tried to disarm the rifle they accidentally shot her again. At some time she was laid on her back on a hard floor and given cpr. This would explain the blood from her mouth and as her head was tilted backward it explains the blood running up to her eye. Her head was not in that position in any of the photos. Also at some point she was placed in the recovery position. This would explain the blood stain forming on the left side of her body as she lay on her left side.
The sequence of these actions I cannot confidently say?