The Minnesota Zoo pathologist on Friday completed a follow-up investigation into the death of the zoo's baby dolphin in early February and could find no specific cause of death.

Taijah, an Atlantic bottlenose dolphin born at the zoo in 2010, died of complications from a stomach ulcer, and zoo officials were hoping to learn more about why it happened. It was the third baby dolphin to have died at the zoo since 2006.

Kevin Willis, the zoo's director of biological programs, said earlier that the deaths have not followed a pattern that might suggest something the zoo could change in how the animals are cared for or housed.

The final report on Taijah from the pathologist said: "The cause of death is uncertain. It may be speculated that the animal lost significant amounts of blood from the gastric ulcer. The cause of the ulceration was not apparent."