The cause of death of a beluga whale that died at the Georgia Aquarium is still unknown.
Marina had fallen ill at the aquarium and died early Saturday morning.
It may take months for scientists to analyze the whale's tissue samples and determine a cause of death, said spokesman Dave Santucci.
Scientists from the aquarium, the University of Georgia and the University of Florida began the medical examination into Marina's death on Saturday,
The whale's central nervous system will continue to be a focus of the investigation, Santucci said. Officials previously said the whale increasingly showed disorientation in her swimming behavior and she stopped eating on Nov. 22.
The initial examination did reveal that Marina appeared to be much older than her previously estimated age of 25.
"She was in a late stage of life," Santucci said. "Age is not a cause of death but it is a major factor in the body's ability to fight" disease and injury.
Marina was the second-oldest of four beluga whales at the aquarium. Marina was among three beluga whales that were transferred in November 2005 from Wildlife Conservation Society's New York Aquarium.