CNN -
Lee Lee, 24, died at the Memphis Zoo earlier this week, according to officials.
Memphis Zoo CEO Matt Thompson said during a news conference Friday that the panda died early Wednesday in his sleep after spending nearly 20 years at the facility.
"The name Lu Li translates to Happy Happy, and his name perfectly reflects his personality," the Memphis Zoo said in a statement.
Thompson added that the cause of the panda's death was not yet known. Senior veterinarian Dr. Felicia Knightley said the zoo's veterinary team and a group of panda experts from China will complete a post-mortem examination "with the intention of finding a cause of death".
Thompson described Lou Li's death as "sudden and unexpected" and said video footage from the days leading up to his death showed no indication of his illness.
The death comes months before Lu Li and the zoo's female panda, Ya Ya, are due to be returned to China as the Memphis Zoo's giant panda loan agreement with the Chinese Association of Zoos expires in April. Thompson noted that the Chinese Society was the first to be informed of Lu Li's death.
They have been very supportive and work closely with us on this. They are, of course, very sad news about it. "They have been very understanding and are a great partner," Thompson added.
Giant pandas typically have a lifespan of 15 to 20 years in the wild and may reach about 30 years in zoos, according to the Smithsonian National Institute of Conservation Biology and Zoos. These animals are native to central China, and are generally rare all over the world.
"At least 1,864 giant pandas live in their native habitat, while another 600 pandas live in zoos and breeding centers around the world," the Smithsonian noted.
The Memphis Zoo hopes to welcome a pair of younger pandas in the future, according to Thompson.