but the thing is, the parents didn't go straight to the flat.
The boyfriend had been there for hours before they came to the flat and that's assuming they came as soon as he'd called to say that he'd reported her missing.
So that would imply that the boyfriend came home, didn't touch anything at all in the flat for at least four hours and that it was in the exact state Joanna left it in for the parents to have noticed.
That doesn't make sense. You wouldn't come home and not touch or move anything would you.
He'd found her keys, her bag and her phone so he must have moved things, so the flat wouldn't have still been in the state Joanna left it in.