McCanns Case: How can a dog sniff through concrete?
Philomena McCann's discription of the cadaver dogs, "what are they Lassie? They could be barking at anything."
The decomposing body is liquefied from the inside, by enzymes in the muscle tissue. This causes the body to swell, and give of the gas Hydrogen Sulphide. This what the dog will pick up on.
How can a dog sniff through concrete?
A child's remains were discovered under several inches of concrete at a former children's home in Jersey after police bought in dogs to search the site. But how can they sniff through concrete?
For Eddie, it's all in a day's work.
When police suspected human remains were buried on the site of a former children's home in Jersey, the springer spaniel was part of the specialist team brought in to investigate.
Jersey Police said the seven-year-old dog located parts of a child's body even though they were buried under several inches of concrete. So how did he do it?
Eddie is an enhanced victim recovery dog and is specially trained to detect the scent of human remains. He is able to smell through solid materials, like concrete, because of scientifically-based training techniques.
It's this training that sets him apart for standard police sniffer dogs, which are able to detect human remains in shallow graves. The springer's nose is more sensitive and he is called in on more complicated cases.
The specialist training techniques - which are highly confidential - were developed by Eddie's handler Martin Grimes, along with the UK's National Policing Improvement Agency (NPIA) and America's Federal Bureau of Investigation (FBI).
They are scientifically based and rely on how dogs smell and the chemicals involved.
Canines are known for their outstanding sense of smell, estimated to be 10 times stronger than a human's. Like us they smell using special receptors in the nose, which react to tiny chemical scent particles in the atmosphere and send a message to the brain.
Dogs can smell so well because they have an estimated 200 million such receptors, compared to five million in a human nose. The extra receptors mean canines are able to distinguish between different smells much more acutely.
"We don't discuss what the training involves, but it's a lot more than putting bits of meat on the ground for them to hunt out," says Mr Grimes, a retired South Yorkshire Police officer who now works as an independent consultant.
"A standard sniffer dog is like a basic tool. An enhanced dog goes through much more training and is a lot more discriminating about smells, basically it's nose is super sensitive. It's also about getting the dog to really focus on a task."
While rare, Eddie and partner Keela are not the only enhanced victim recovery dogs in the UK. The Metropolitan Police and forces in Surrey and Greater Manchester have them. But what sets these two springers apart is that they work exclusively in this field, says Mr Grimes.
"Other dogs have to do other police duties but mine work full-time in this area, making them very sharp and highly skilled."
The dogs have been used by police forces across the world and were called in to help with the Madeleine McCann investigation.
Both are springer spaniels, but the breed is no better suited to the job than any other. A dog just needs to show a keen sense of smell and it's the training that makes them good enhanced victim recovery dogs, says Mr Grimes.
Eddie was bred by a specialist search-dog breeder and Keela came from the West Midlands Police breeding programme.
Both live with Mr Grimes and have a normal life outside of work. He is currently training two new dogs, Morse and Lewis.
In the Jersey case, parts of a child's body were found on Saturday. The remains are thought to date from the early 1980s. Police have yet to say whether they are male or female.
Daily Mail: Gerry's fury at 'bungling' dog handlers
Gerry McCann was furious when he saw video tape of British police dog handlers examining the family's hire car, a source revealed today.
He believes they bungled the moment a sniffer dog allegedly detected "the scent of death" in the back of the Renault Scenic.
The animal's reaction led to Mr McCann and his wife Kate being named official suspects by Portuguese officers investigating the 3 May disappearance of their daughter Madeleine.
But Mr McCann has told his legal team that the dog walked around the car and was beginning to walk away but it was brought back by its handler and held at the boot when "it went rigid".
A source close to the McCanns said: "Gerry saw it on the tape. Vehicles were lined up in an underground car park. Gerry says the dog went up to the Scenic, sniffed around it and went to head off.
"But he says he watched the dog brought back to the vehicle and finally it reacts around the boot area.
"Gerry was open-mouthed when he saw it. He feels the dog was manoeuvred into a position where it could react. To Gerry it looked like the dog was being encouraged to react in certain places of relevance."
Portuguese detectives showed the video to Mr McCann during lengthy interrogation. The dogs were used to look for human remains in the McCanns' Praia da Luz apartment and in several vehicles seized by police.
According to the source, the dog spent seconds around vehicles owned by the other official suspect in the case, Robert Murat and his family and friends, but was kept for a minute at the hire car, rented 25 days after Madeleine vanished from the family's apartment in Praia da Luz.
The boot was later said to show traces of Madeleine's DNA and evidence that a corpse was kept in there - claims disputed by the McCanns who have had their own tests carried out.
The family have compiled a dossier of evidence to disprove the police case against them. This includes analysis of evidence provided by the sniffer dogs which they claim is unreliable.
Sun: Maddie sniffer dog 'was rigged'
The animals appeared to detect traces of the four-year-old’s DNA in the Renault Scenic — rented 25 days after she vanished.
This lead to Kate and Gerry, both 39, being made suspects in their daughter’s disappearance in Praia da Luz, Portugal.
But Gerry, from Rothley, Leics, who was shown a video of the search, told lawyers the animals’ evidence was unreliable.
A source close to the couple said last night: “Gerry says a dog went up to the Scenic, sniffed around and went to head off. He watched the dog being brought back to the vehicle.
“Finally, it reacts around the boot area. Gerry was open-mouthed at that, he feels the dog was manoeuvred into a position where it could react.”
Related: Sniffer Dogs used to seek Madeleine prove again their effectiveness