ATLANTA (AP) - A 50-year-old gorilla who became a beloved figure at Zoo Atlanta after spending several decades in a Washington state department store has died, zoo officials said Tuesday.

Ivan, a male western lowland gorilla, never regained consciousness after he was put under general anesthesia Monday for a diagnostic assessment, Zoo Atlanta said. The zoo says the geriatric ape had recently lost weight, seemed to lack appetite and had a respiratory illness.

"When it became obvious that our efforts to modify his diet and his existing medication regimen were not resulting in significant improvement, it was necessary to perform a diagnostic procedure to determine the underlying causes of Ivan's condition," said Hayley Murphy, director of veterinary services. "General anesthesia carries a degree of risk in any veterinary procedure, but these risks are compounded in an individual of Ivan's advanced age and delicate condition. We are heartbroken that this proved the case, and Ivan did not recover from the anesthesia."

Ivan had lived at Zoo Atlanta since 1994. He was born in the wild around 1962 in what is now the Democratic Republic of the Congo. Wildlife traders sold him to the owners of a department store in Tacoma, Wash., in 1964. Three years later, he was moved to an indoor enclosure at the store. Known as the "Shopping Mall Gorilla," Ivan had thousands of fans and visitors.

By the mid-1990s, a national movement had begun to have the solitary ape relocated. Facing pressure from zoological and animal rights communities, the store in 1994 donated Ivan to Seattle's Woodland Park Zoo. He was moved to Zoo Atlanta on permanent loan in October 1994.

Ivan was compatible with a number of female gorillas who lived in the same habitat over the years and was seen mating at least once, but he never fathered any offspring. He formed close lasting bonds with his keepers.

"This is a tremendous loss to the Zoo Atlanta family, and it is a loss that spans two coasts. It's because of the great love Ivan inspired in his years on the West Coast that the wheels were ultimately put in motion to have him join us here at Zoo Atlanta," said Raymond King, president and CEO.

Ivan was known to dislike cool or damp weather and was often seen using a burlap bag to protect his feet from dewy grass. He also seemed to enjoy painting and was known to "sign" his works with a thumbprint.

Gorillas are considered geriatric after the age of about 35. Ivan was one of four Zoo Atlanta gorillas who are 50 years old or older. The other seniors are females Shamba, 53, and Choomba, 50, along with Ozzie, 51, the oldest male gorilla living in captivity in the world.