As authorities continue the probe into the sets of remains found on a desolate Long Island beach highway in a case believed to involve more than two killers, one investigator has proved invaluable to the search: an 8-year-old German Shepherd named Blue.

Blue, as the cadaver dog on duty during a frigid afternoon last December, went on to uncover four bodies near Jones Beach -- the first of four in what would become a months-long investigation that would eventually uncover 10 sets of human remains.

At the time, the Suffolk County Police were down to just one dog trained with that specific skill. The other two had been retired and the police were in the process of training new ones, according to an officer in charge of the Special Patrol Bureau, which includes K9s, cops said.

"Dogs are able to find these remains much more rapidly and in some cases remains that would never otherwise be found if we were searching the area with people, visibly searching for something," said inspector Stuart Cameron, commanding officer at the Suffolk County Police, who noted the county trained two more dogs in the wake of the discovery.

Currently, there are 19 K9s that specialize in either explosive detection, narcotics detection and three that specialize in cadaver detection. The dogs, mostly from Eastern Europe, are selected when they are 1- to 2-years old and are chosen based on their health and temperament.

Cameron said they are looking for "green dogs," or dogs with no previous training, and canines that are neither too aggressive nor too docile.

The dogs undergo 16 weeks of training, followed by eight to 10 weeks of training in their specialty. They are regularly retrained once a week for patrols, and every two weeks in their specialty.

For dogs like Blue, and his fellow cadaver detector, Hungarian-born, 5-year old Knight, who also uncovered two sets of human remains, their training involves searching for a cloth or rag covered in bodily fluids that simulates the smell of a decomposing human body.

Humans experience the world with their eyes "but a canine, their sense of smell is estimated at 1,000 to 1,000,000 times more sensitive than a human's," Cameron said.

Cameron said canine units have found bodies that were underwater (the dogs smelled the air bubbles that drifted to the surface), buried underground and under snow.

Right now, the canine unit is not actively searching the Long Island beaches for further human remains, but they may go back if necessary, Cameron said.

When the canine unit completes a task, the dogs are rewarded by they handler with playful treatment. "They are very high drive dogs, they want to work, but for them really work is kind of play,” Cameron said.

Canine Facts:

• All Canine Section dogs are male German Shepherds imported from Eastern Europe.

• Each dog lives with his handler and usually retires at age 10.

• In the 1960s, the dogs were only used for overnight work, usually working from 8 p.m.to 4 a.m., but now they’re on call 24-hours.

• The Suffolk County Police have two full-time dog trainers.

• The Suffolk County dogs assisted at recovery efforts on Sept. 11.