QUESTION FOR YOU and then I'm off: Can the police question the doctor or review the files for Marion's visit? Have they the authority in Australia to do that?
I believe they can but would need authorization to do so, they would need to give weight of evidence on why they need to before it was granted, like with a warrant.
My take on this, first they were hinder by the bank ID - Marion's response confirming she was voluntary missing (assuming this happened) - police then have to back off.
Investigation is resuscitated - They then find the name change, the re-entry card and not contacting her family - this backs up the above first investigation - voluntary missing.
The police can not seek authorization to view someone's medical files when all of the facts point to voluntary missing. that would never get approved.
Fast forward, we now have that she didn't touch her super or retrieve the money from the UK, this may now be used as evidence that she is dead or come to harm, my assumption is these facts have opened the door a little more for the police as they can use this as evidence to investigate the case further, possible because even if they think she is voluntary missing, it likely she is also dead so there will be no repercussions for the police if they find she was voluntary missing. Of course now its likely to late to retrieve the Dr files, unless the timing with Gary and the super and UK money came to light and he used this information to retrieve them.
Above is just my take on this