Cadaver Dog: Mrs McCann, who was interviewed for 11 hours, could not immediately explain the reaction of the dog but her legal team concluded later that the scent could have come from her contact with corpses while working as a GP. Kate McCann worked one and a half days per week!

The dogs smelt death and blood..Behind the sofa
In the wardrobe
On one of the childrens tee shirts
On Kates trousers
In the boot of the hire car
on the key fob of the hire car
on Cuddle cat

to the exclusion of all other locations.

Now.. the dogs might have been wrong once (and these are good dogs with an excellent track record) .. but wrong that many times in a row in that many connected places ?

http://steelmagnolia-steelmagnolia.blogspot.com/2011/04/mrs-mccann-who-was-interviewed-for-11.html