Something a couple of posters said earlier really got me thinking. It always puzzled me why GBC would have rung the police so early in the morning. Waytoo early. It would have been better for him and brought him more time if he was able to say he last saw her leaving for the conference, then call the police late Friday night, and let the police find her car in some wayout place, or over a cliff.
If it was a neighbour who called police I'm sure the police would treat it confidentially and not let GBC know who it was.
It fills in lots of gaps for me if it was the neighbours or a friend of Alison who rang the police. Maybe they did not only hear something but see something that worried or frightened them.
The police may have arrived unexpectedly, and like a poster said possibly did find GBC or another family member cleaning cars or vacuuming, especially when your wife's car is there but you can't produce her. Maybe saying she went for a walk was the best he could come up with.
What amazed me was that there must have been at least 6 police cars arrive at the GBC house the morning she went missing.
This could have been discussed previously, so forgive me, but had there been a reason for them to pounce so heavily? Had Allison gone to police about something in the days leading up to her murder?