"I am a cadaver dog handler and I think there's a very high chance of false positives in this case. The first thing to consider is that there were two dogs, but there was only one handler, and most false alerts are handler error.
As others have noted, there were huge breaches of search protocol in the vehicle search. Any dog will eventually give a false alert if you keep telling it to work the same area over and over, which is what happened. It's been awhile since I read it, but I recall that the pattern of alerts in the apartment also made me suspicious that they were reworking the dogs over the same areas over and over again in there. So they were basically asking for a false alert.
Even if the alerts were correct, though, we're talking about hotel rooms/vehicles where who knows what could have occurred. Someone crashes their bike and bleeds all over their clothes, then drops them in the trunk of the car and the fluid soaks into the fibers of the upholstery (or behind the sofa, or anywhere else the dogs alerted)? That could be enough to get a cadaver dog alert even though it has no relevance to the McCann case.
Dogs are pretty amazing and I have a tremendous amount of faith in mine, and all of their alerts have been backed up by forensic evidence. I'd still never convict someone just based on the evidence they provide, especially since on a few occasions that forensic evidence showed that, while the alert was correct (there was actually blood there), it had nothing to do with the actual mission we were on."
https://www.reddit.com/r/Unresolved...uestions_about_madeleine_mccann_case/dl0bc5t/