"Person A is around the OC, sees the McCanns leaving the apartment by the patio, knows it is unlocked. Waits until they gone into the tapas. Drive up to back entrance of 5a, nips into apartment, picks up Madeleine (if she wakes just tell her taking to Daddy), out to the car, drive off. Job done".
I haven't excluded a lone perp.
I have a few problems with
(ETA: Sorry, Slarti's) scenario above, though. Perhaps because I'm examining it as an opportunistic abduction.- "Person A is around the OC, sees the McCanns leaving the apartment by the patio, knows it is unlocked."
Yes, easy enough.
- "Waits until they gone into the tapas."
Assuming Gerry did see her in bed a bit after 9 pm, it couldn't have been as soon as they'd left for dinner. Someone hiding behind the children's door seems highly improbable, IMO. If someone had been hiding in the flat, then the parents' bedroom would seem feasible, though risky. Hiding in the garden and keeping an eye on the T7 at the Tapas might be a possibility.
At 9.30 pm ish Matt noticed a bit of light coming in, but no slamming doors or whooshing curtains. If she had already gone, then there would presumably have had to be a lull in the wind and he simply didn't pay much attention to the windows.
An alternative leaves being taken between Matt's visit and Kate finding her missing at 10pm.
- "Drive up to back entrance of 5a, nips into apartment"
A couple of statements indicate that there were parked cars nearby, but a bit vague.
If a perp went in and out via the patio and the car was nearby, why open the shutters and window? Doing so would make more sense to me to disguise having a key to the front door. Or having an accomplice in an intended burglary situation at the front, or had raised them in the assumption that the door was locked prior to checking it and finding it could open (this would mean exiting via the front, whichever door was used for entering).
- "picks up Madeleine (if she wakes just tell her taking to Daddy).
For a long time, I couldn't imagine M not screaming her head off if she'd woken up. However, a little girl was taken from her bed in France this past summer and no one in her family sleeping nearby heard a thing. Threatening to harm the twins might have have made her keep quiet if the perp spoke English.
One possibility is that she wasn't in bed at the time, e.g., had got up to go to the loo and was grabbed at that point, with a hand over her mouth to keep her quiet.
That raises the question of why not just flee at that point and leave her behind? A run-of-the-mill burglar might have done, but one who'd changed "plans" might not.
If she'd been left unconscious , there could be a fear of evidence (being able to describe him/her, or forensic evidence). If dead, same fear of forensics, plus a far longer sentence than an intended burglary.