I'm of the view that Jeremy may be innocent.
Let's look at Sheila - the model.
Imagine she has killed the family.....she may have been covered in blood, however, having a bath or shower, would easily resolve that problem.
She is the sole survivor, she bathes, does her hair and applies make up. She is preparing for the final Act. Suicide. Her thinking is not 'normal', after all, she has (supposedly) just massacred her entire family - barr Jeremy.
The police are outside, she is well aware they want to speak to her. She could at this stage, have begun to 'come to' and realise the full enormity of what has happened - and what is about to occur soon (armed police will enter and she will be looking at a life sentence behind bars).
Her choices are limited. The thought of life imprisonment is not an option right now - after all, her dear sons are no longer with her. The 'better alternative' is to now go and be with her sons, and the rest of her family.
Being the model, it is important she look her best - to those who find her and for her sons when she next sees them.
I can see no problem in Sheila 'preparing' herself for what is to come. Sadly.
This post may seem quite odd and irrational, but if Sheila 'did' do this, we can all agree her thinking was not that of a rational person.....therefore, her actions would not be rational either.
With her mental illness, the drugs she was prescribed etc, I cannot point the finger at her easily. Today we understand more about mental illness.....if anything, I feel for her, she never got the help she really needed.
It does not settle easily with me to point the finger at Sheila at all - I find it an uncomfortable thought. Therefore, if I'm of the view that Jeremy is innocent, and I'm uncomfortable with the thought of it being Sheila - then I cannot dismiss the idea of it being someone else (not brought in by Jeremy either).
This would be a professional and over time, I have read/heard things, which in my view, answer more questions than not.