BAR HARBOR – Scientists have completed their investigation of the body of a young pilot whale that died in the Penobscot River over the weekend.

However, the investigation shed little light on the whale’s mysterious behavior in coastal waters in recent weeks. On Thursday, Judy Allen, a scientist at Allied Whale, called the necropsy – similar to an autopsy – “fairly inconclusive.”

Researchers inspected the 12-foot-long animal inside and out, but found only an injury to its lower jaw, which could have been caused by the whale’s repeated attempts to beach, Allen said.

The juvenile male whale’s stomach was empty when it was found, but its protective layer of blubber had not been depleted, so scientists do not believe that the whale starved to death as a result of its injury.

“It wasn’t emaciated, and there were no obvious signs of disease – nothing jumped out as a likely cause of death. You just couldn’t draw any conclusions,” Allen said.

Local residents have tracked the whale’s progress since it first appeared near Stockton Springs almost three weeks ago. The long-finned pilot whale is not a species that is commonly seen off Maine’s coast, although it is far from rare in the North Atlantic.

The whale traveled upriver, nearly to Bangor, enthralling residents all along its journey. Allied Whale staff members were called to rescue the animal when it repeatedly beached on the sandbars and mudflats near Cape Jellison.

Despite the scientists’ best efforts, the whale would not return to the Atlantic. Instead, it spent its final three weeks in shallow water, floating on the surface and swimming in tight clockwise circles.

This odd behavior indicated to scientists that the whale was probably ill. Pilot whales are a particularly social species, traveling in pods of 50-100 animals, so a solitary animal is typically suffering from disease and near death, scientists said.

A fisherman found the whale’s body floating in the Penobscot River on Tuesday morning and turned it over to Allied Whale, where staff members completed their investigation that evening.

Tissue samples from the animal’s brain, blubber and vital organs have been preserved. Later this week, the samples will be sent to a lab used by Allied Whale’s parent organization, the marine mammal strandings program at the National Marine Fisheries Service, Allen said.

Tests will require several weeks to complete, and the samples may not even yield useful data because the whale had been dead for several days when the tissues were collected, she said.

To guarantee the best results, researchers prefer to test tissues within 24 hours of an animal’s death. Scientists have received conflicting reports about the animal’s whereabouts on Saturday, thus are not sure when the whale actually died. They listed the time of death only as the weekend of June 16-17.

“Some things can only be detected if you’re able to get these samples within a certain time period,” Allen said. “There may be a limited amount of knowledge available.”

The whale’s body now rests in a cage submerged in the water just off Mount Desert Island. Fish and microorganisms in the water will eat away its flesh, leaving a clean, perfectly preserved skeleton, Allen said.

Once prepared, the skeleton will be displayed and used for study at College of the Atlantic.