COAL VALLEY, Ill. -- The youngest of Niabi Zoo's four-giraffe herd has died unexpectedly.

Jabu, a 3-year-old male who has been at the zoo for about two years, was found dead around 5 a.m. today, Zoo Director Tom Stalf said.

"What an icky day it's been for us," he said. "He was the littlest one. He was under a veterinarian's care - was a little lethargic."

The animal's body was transported to the College of Veterinary Medicine at the University of Illinois for a necropsy (animal autopsy) and pathology report.

"At no time did anyone feel like, uh oh, this animal isn't going to survive," Stalf said, adding that his wife, zookeeper Colleen Stalf, checked on Jabu Tuesday night, and he appeared to be OK.

"We sent him to the University of Illinois for two reasons: make sure everybody else is OK and not at risk and, also, we just want to know," he said. "I feel this (the cause of death) is going to be something they find.

"We don't feel the others are in trouble. They show no signs of illness, but Jabu did."

Stalf said the necropsy results could be almost immediately available, provided the cause of death was something fairly obvious. If tissue samples and other tests are required to find the cause, he said, it could take weeks.