Following all these helpful links and filling in the blanks in my previous knowledge I see that we seem to have :
- head bruising.
- no significant laryngeal damage;
- deep bruising to the muscles of the neck;
- marks to back and front of neck consistent with two-handed strangulation;
- a pathologist who rules out instantaneous death, can't rule out a very rapid death but shows no inclination (and rather the contrary I think) to prefer the 10-second version to the 90 second version.
All of this for me conjures up a killer standing in front of his victim and holding her neck with the thumbs at the front, to either side of the larynx, the rest of the fingers at the back pressing hard against them. The result is more ischaemic than asphyxial but allowing for victim resistance is very unlikely to be over in less than ten seconds unless he has already rendered her unconscious by striking her head. I think that if the rapid scream-scream-thud sequence heard by the witness is accurate and was Joanna, it was not her death that he heard but rather attempted strangulation from which she wriggled free, screaming again and being struck hard, blacking her out long enough for him to improve his grip and strangle unresisted.
Just my impression from insufficient data, you understand. The judge and the jury have heard it all; I haven't.
How about this for something way off the mark but feel free to rip it to shreds:
How about he believes she is a burglar but doesn't actually see her properly through the kitchen window. Perhaps he can hear her bumping around in the kitchen, or even be worried by the fact her kitchen light is on, and they (her and GR) were supposed to be away at the weekend?
She also notices him (or just the security light) but due to her lighted kitchen and the fact her security light came on, she doesn't recognise him as being VT.
As for the reason why VT would be there anyway. If he was in his back bedroom he might have heard something or seen the light coming on from the direction of her back bedroom window. Or he could have heard noises from anywhere in his flat coming from next door.
Back to the encounter...
So JY approaches the front door to look through the spy-hole. VT approaches from the outside and kicks the door open hard because he's a bit fearful of what he might encounter. At the very same moment she screams as the door is being flung open fast, but doesn't respond quick enough to stop it opening and gets hit by it.
Him kicking the door open (perhaps JY left it ajar by accident?) knocks her back, thus she gets a bruise to her chin and it breaks her nose on the very tip (as stated by the prosecution in court) as well as receiving bruises to her face.
This could also explain some of the bruising to the back of the head if she was knocked out and fell backwards in the hallway.
He then realises that he's knocked her out cold when he enters the flat and notices blood or bruising and he panics. Could it be in his panic he strangles her by shaking her trying to revive her.?
Perhaps he thinks he's given her brain damage?
If she is limp, how much force would someone need to do damage/strangulation?