No, because Jeremy confessed to Julie at Blazer's Restaurant, Blackheath.
Didn't Bamber confess on the day after the murders with the Matthew story Steve?
Then however,she apparently did not get a chance to quiz Bamber any further for several weeks because there was always someone with him.Were there three of them in bed? Naughty!
Anyway,it seems her guilt for Bamber got worse as she realised his feelings for her had waned and no marriage ceremony was going to take place.
The guilt over the murders and the pain of the break-up apparently went hand in hand.
Or in reality,was there only unbearable pain and grief due to the relationship coming to an end,causing Julie to tell her friends how evil JB was.
The final insult from JB was telling Julie that he was too busy to go on holiday with her,that was indeed what sent her over the edge,breaking down and seeking some comfort from Lizzie and co,.
But then with her mind muddled with pain and a need for revenge she blurted out claims of JB's plans to kill his family and the Matthew story [spoken by Bamber in jest of course,if spoken at all]
So,persuaded by her friends Julie went to the police to cause him some hurt,never intendng to get him banged up.But alas,Stan was desperate for evidence by then and even when the Matthew story was proven false he could not let it go,he convinced Julie that JB actually shot his family himself and had not been talking in jest about his plans to murder them.
And whether Julie wanted to help the police or not,by then she had no choice due to their knowledge of her own crimes.
And in effect,she became the most important witness although it held very very little real evidence against JB,only a story which you have to suspend belief slightly in order to accept as the truth.