No idea about that. I have not watched the video in full just bits. Maybe whatever smell he was alerting to(I am not suggesting this was definitley cadaver odour by the way as that is impossible to know) could have been less concentrated on the toy.
I have heard/read one of the biggest factors that cause these dogs to give false alerts is cueing by the handler. I am not suggesting this is definitley what Grimes did as some direction is standard I think, but it seems from the brief reading I have done this can be a problem.
Consider this lordpookies.
The FBI have their own cadaver dog handlers, men they had trained and knew the standard of their work. Yet they decided to bring Martin Grime, at great expense I'm sure, to America to help them find evidence of death in high profile cases. Now why do you think they did that ? They had their own men, so why go to all that unnecessary expense ?
Why, after viewing the videos we have all seen, did the FBI decide Grime's work with his dogs was of such a high standard that he would be an asset to their team ?
Why, if the faithful can see all the unconscious cuing that Grime was using towards his dogs, didn't the highly trained men of the FBI see it ?
Why if he was not executing the searches in a professional manner did the FBI employ him at all ?
Do you really think the FBI would employ a dog handler who was prone to unconscious cuing and whose handling of his dogs was dubious ?
