A police dog trained in finding cadavers as well as an underwater camera were brought in Monday to help find a Sound Beach kayaker last seen five days ago disappearing into the waters of Lake Ronkonkoma, Suffolk police said.

The German shepherd and his handler got on a boat that navigated the lake looking for Kevin Conley, 40, police said.

"His thing was to smell the bubbles" and the boat waves for the scent of human remains, said emergency service Officer Tobias Monaco, one of the searchers.

At one spot, the dog indicated he smelled something, the officer said, so the underwater device, which has front and back cameras and lights, was lowered on a 250-foot tether. "We went up and down and we didn't find anything," Monaco said.

The canine unit was prepared to go ashore if anything on land caught officers' attention, said homicide Det. Lt. Kevin Beyrer.

Lake Ronkonkoma is Long Island's largest freshwater lake, and parts of the shorelines are dense with vegetation, making it easier to reach by boat, instead of by land.

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Beyrer said he does not believe the body has washed ashore but police want to try anything to find Conley: "If that is something that doesn't help, at least we've utilized it."

It marked the fifth day of searching for Conley, last seen about 3:30 p.m. Thursday struggling in the water and sinking after his life vest popped off. The lake is 15 feet deep in most parts but as deep as 65 feet in certain places, said the state Department of Environmental Conservation.

The marine bureau and the emergency service section Monday continued using sonar and divers, police said.

The underwater camera, purchased with federal anti-terrorism funds, showed a sandy bottom, thick with vegetation in some parts, Monaco said. The device at times got caught in weeds but was used for three hours. "We had a good picture of the bottom," Monaco said.

It was not immediately clear if the dog and camera would be used again Tuesday. One issue Monday was the height of the hull -- officers were trying to get a lower-profile vessel so the dog could put its nose closer to the water, Monaco said.

On Thursday, divers from the marine bureau and several fire departments searched until dusk. Friday, swimmers found Conley's kayak near where he disappeared and brought it ashore, police said.

By Sunday, a police spokeswoman said "sporadic searches" would be made as resources allow.