The two dogs, one trained to detect human blood, the other the smell of dead bodies, were taken to numerous locations, but only gave alerts inside the McCanns’ holiday apartment. The cadaver dog later gave another alert signal while inside the Renault Scenic hire car that the McCanns had rented 24 days after their daughter went missing.
Analysis of hair and other fibres taken from the hire car and apartment were analysed by the UK’s Forensic Science Service. Four days after the FSS analysis was complete, the McCanns were made arguidos, with Portugese officials citing DNA evidence as one of the grounds for suspicion.
It later transpired, however, that neither the sniffer dog or DNA evidence were as watertight as some observers assumed.
Sniffer dog evidence has been the subject of research questioning its reliability, and in one US court case, a judge agreed with analysis of three cadaver dogs’ performances which found they were wrong 78 per cent, 71 per cent and 62 per cent of the time.
