91. Professor Knight, another defence witness, lent support to Dr Bradley's evidence as to the feature of excessive violence in parental killings. He also spoke of instances where the murderer (having killed their spouses in most cases) has then gone about some mundane or "ritualistic" task, such as cleaning up before committing suicide. In cross-examination he accepted the proposition contained in an article, which he himself had written some years earlier, that "women almost never commit suicide by shooting".
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So Sheila may have committed the massacre naked or in underwear. As suggested by Lookout.
Then had a shower & changed into the exact same nightie you would expect her to have gone to bed in.
Not sure where Sheila read about pre suicide ritualistic cleansing. Certainly not in June's bible which was next to her.