It has already been explained, Benice.
Keela only reacted behind the sofa. Eddie reacted in 3 other places and, behind the sofa, possibly because of cadaver scent and not because of blood. The general scent wasn't blood. We know that thanks to Keela.
Would it be reasonable to imagine Prof Harrison MBE, in an attack of madness, thought human remains were decomposing in the flat ? Why do you think he called the dogs then ?
Imo he wasn't properly looking for Madeleine's blood (even if found in the flat, it was proof of nothing), he was just contemplating the possibility (a study hypothesis) that both dogs would (or not) react on the same spots, the blood eventually revealing identity through DNA. Not really a proof Madeleine died, but a very solid indication.
If you're the person who cleans your place, you know were the dust is. It's a bit the same with volatile molecules, they're pushed by draughts towards corners and there they stay. This is what Mr Grime explains in the video. The same phenomenon exists in trailing because of the wind.
Anne, Grimes always sent Eddie in first. If he didn't alert, Grime didn't deploy Keela at all, because he knew that if any blood was present Eddie would have alerted. If Eddie did alert he then sent Keela in. If she alerted in the same place then Grime knew this could be not a cadaverscent alert, because Keela only alerted to blood. So whenever both dogs alerted at the same place - he assumed blood. The key fob - to which both dogs alerted, is an example.
If Keela did NOT alert at the same place, then Grime assumed Eddie may have alerted to cadaverscent. However, because of all the different scenarios of WHY and HOW cadaverscent could be present - scenarios which would be entirely unassociated with Madeleine, and because cadaverscent can also come from material that is from living people, the alert on its own does not and cannot prove that a cadaver was ever at that place - UNLESS corroborating evidence was found. This did not happen.
Quote from Martin Grime - for the millionth time
My professional opinion as regards to the EVRD’s alert indications is that it is suggestive that this is ‘cadaver scent’ contaminant. This does not however suggest a motive or suspect as cross contamination could be as a result of a number of given scenarios and in any event
no evidential or intelligence reliability can be made from these alerts unless they can be confirmed with corroborating evidence.End quote
None of Eddie's single alerts were confirmed with corroborating evidence.
Why don't you believe Martin Grime?