So why does Bamber invent a call that does not fit the crime scene and why did the police not pick up on this at the time?
If Bamber's first shots kill Nevil what was his plan?
Easiest plan was -
Twins killed in bed.
Sheila shot out of bed.
Nevill and June negated in bed.
Nevill or June stagger or are pulled out of bed onto the bedroom floor.
Bedroom phone taken off the hook.
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That way Sheila is running amok. Nevill or June are able to react by phoning Jeremy.
He was successful with June - Negated in bed, able to leave the bed but no threat. Nevill put up too much resistance.