Scientists yesterday morning captured and examined three dolphins from the coastal waters off Virginia Beach for evidence of the condition that has been killing dolphins along the East Coast since early July.

Before releasing the dolphins, the scientists drew blood samples and, from one, drew fluid from its chest cavity.

"I'd say we've made a significant step forward today," said Joseph L. Geraci, a specialist in marine mammal veterinary medicine from the University of Guelph's Ontario Veterinary College, who is heading the investigation of the dolphin mass mortality.

As a result of the procedure, Geraci expects "to determine in some measure what the clinical condition of these animals is and to have a better understanding of the progression of the disease."

All three dolphins showed the early stages of the mouth problem -- ulcers, especially -- that has been common in dolphins that have come ashore, Geraci said.

The dolphin whose chest cavity was abnormally filled with fluid, another common characteristic of the illness, is "certainly not a healthy specimen and probably will not live very long," Geraci said.

The scientists, including a team of marine biologists from Sea World in Orlando, Fla., had hoped to isolate two dolphins with apparent signs of the illness from a group of about 12.

"What is curious is that we got three out of three," Geraci said.

The blood samples were sent to the East Virginia Medical Center and the Virginia Beach General Hospital to be processed for hematology and blood chemistry.

According to Geraci, the test results, which are expected this afternoon, should help scientists "determine if there is an infection, its duration and perhaps obtain a lead into the type of organism that might be responsible."

But, he said, the results will be "rather preliminary."