.... The story is roughly this. After Joanna arrives home on the Friday night, she is invited (for instance by a close neighbour) to have a glass of Christmas sherry with him. She accepts and goes to his place, wearing shoes on her feet and taking her bag, but leaving in the flat her pizza which she was getting ready to eat.
The neighbour knows Joanna and knows that Greg is away for the weekend. He does not know that Joanna has been recorded this evening on CCTV and he does not know that she has a till receipt in her handbag. Neither does he know that she made a call and sent a text after leaving her office party.
I imagine him attacking and strangling Jo, in his own home, a little after 9 p.m. on the Friday evening. Once the deed is done, as a close neighbour, and having obviously no genuine alibi for the time when he is committing the murder, he fears that he will be interrogated and suspected. He wonders what to do to divert suspicion from himself. He is perhaps not strong enough to lug the body very far. He thinks of dumping it straight away with all the personal effects at a safe distance, but he realises that it is likely to be found soon and that the spotlight will be back on him.
It occurs to him that the first person the police usually suspect is the spouse. Greg wont do, as he is away for the week-end, but if the killer can succeed in fudging the timeline sufficiently, Greg might be suspected nevertheless. Failing that, the likeliest possibility to take the heat off himself would be for the police to believe that Joanna was killed in her own flat by an unknown chance intruder.
The killer therefore takes Joannas effects back to her flat to give the impression that she was attacked there. Seeing her pizza, he removes it, to leave the timeline vague as to her meals. Then he has a stroke of genius: he ostentatiously scrubs an area of the floor with powerful bleach, so that the next entrant into the flat cannot fail to notice. This will infallibly give the impression of a forensically aware criminal cleaning up after a murder. This was what convinced the police and family that it was a murder even before there was a body. It was meant to. This was what the Yeates parents saw but were not allowed to reveal.
Finally the killer leaves the flat and returns home where he loads the body into a tarp and takes it to a place of intermediate storage. After Greg is safely back home, he will dump it at some neutral spot he knows for timely discovery that will leave the police unable to determine a very exact time of death.
The rest of the story we know.
