FERNANDINA BEACH, FLA. -- The scientist coordinating the investigation of the rash of dolphin deaths along the East Coast said he realized from the beginning that the mystery would take a long time to unravel.

Dr. Joseph Geraci was contacted by the U.S. government in July to investigate the rash of mysterious dolphin deaths off the Virginia and New Jersey coasts and recently expanded his probe into deaths that have occurred since Thanksgiving in North Florida.

"The day I received the invitation, I was in Virginia Beach with a small group of associates," Geraci said. "When I saw my first animal the day I arrived in Virginia Beach, I knew we were in for a struggle, and I had never seen a condition like that.

"The skin was peeling off the animal. Virtually all its internal organs were infected by an overwhelming bacterial disease. And it was very clear that if this was characteristic of the event we were about to investigate, that the analytical process was going to be complex and take some time.

"I didn't realize how long," he said.

Geraci is a professor of veterinary medicine in the pathology department at the University of Guelph, about 60 miles southwest of Toronto. As a member of the U.S. Marine Commission's committee of scientific advisers, he is coordinating the work of dozens of agencies trying to solve the puzzle.

He hopes one day to be able to say why the dolphins, possibly 2,000 or more, have died.

Geraci says he has done about 1,000 autopsies on dolphins, seals and whales. But he concedes that his knowledge only scratches the surface.

"The whole event has provided me a lot of insight into the nature of the disease processes in a population of dolphins -- in a population of marine mammals. Prior to this study, the only widespread disease that we had observed was in seals and sea lions," he said.

The task force on dolphin deaths has moved its base of operations from Virginia Beach to Marineland, south of St. Augustine, Fla.

Geraci and others are trying to determine whether the dead animals are migratory dolphins that became ill farther north or represent local pods being infected by their northern cousins.

However, scientists have been unable to identify the culprit responsible for the chain of dolphin deaths. And even when they find out, Geraci said, there may be little that can be done about it.