There is a significant reason why he is not guilty.
There is no fully developed post-mortem hypostasis (Lividity) in Sheila's body. Lividity starts to become visible in 2 hours and completes in around 6 hours. These photos were taken when Jeremy was in police custody for over 7 hours. For Jeremy to be guilty, post-mortem hypostasis (Lividity) has to be fully apparent in Sheila as it is June. The fact Lividity is only just barely starting in Sheila shows she died around two hours after these photos were taken. Roughly the exact same time the police broke the door down. Sheila killed herself as the police began breaking down the kitchen door. This made her realise she had no other option but to take her own life.
It does not matter what happened at Jeremy's school, What he allegedly thought of his parents, What mood he was in one particular day at Little Chef, where he went on holiday's or how he liked his eggs on toast. Its IMPOSSIBLE for him to have killed Sheila
No it isn't IMPOSSIBLE!
One thing is for sure either Sheila didn't do anything strenuous before death, such as desperately struggling with her father as Rigor Mortis would have set in straight away, and David says it hadn't as the police moved her arm.
Physical exertion just before death: When someone dies while engaged in something strenuous, such as exercising or attempting not to drown, rigor mortis can set in at once. This instant onset is sometimes called cadaveric spasm. It happens because at the time of death, the person's muscles were out of oxygen energy and ATP.
OR.... Sheila's arm was moved by police because Rigor Mortis wasn't complete after 9 hours.
Timeline of Rigor Mortis
There are many factors to consider when examining rigor mortis in order to come to any conclusions or findings about a person's death. This is the general timeline that rigor mortis will follow under regular conditions:
0 to 8 Hours: The body starts to stiffen, but is still movable
8 to 12 Hours: Muscles become completely stiff12 to 24 Hours: Muscles stay stiff
24 to 36 Hours: Stiffness dissipates and muscles become flexible