According to Julie, Jeremy had proposed to her just prior to Christmas 1984 and she agreed.
According to Julie, Jeremy's parents told him it was time to get married.
According to Julie, June didnt approve of her being with Jeremy.
If we assume that Julie is being truthfull here or at least this was her end of the stick. Then I can make an educated guess that Jeremys parents prevented the marriage, or at leased persuaded him otherwise.
Then the only person who would have thoughts about killing his parents around this time would be Julie. Julie claims that Jeremy was thinking about killing his family around this time. But are they actually Julie's own thoughts that she is attributing to Jeremy?
"I asked him why as I could understand him talking about his parents like that, not Sheila and the twins"Freudian slip. She could understand why his parents had do die.
Its very possible that Julie fantasied about Jermey killing them so they could be together.
Now fast forward to August 7th. Maybe Julie didnt think twice about Sheila being the shooter.
However once she realised people suspected him. Did she rationalise this by thinking he could have
done it so he his parents would not get between them?
Now you might say she would rubbish that idea once he split up with her. However Julie does not think straight and thats the last thing she would do (think straight) once Jeremy had left her.