Mali, known as the "world's saddest elephant," has died at the Manila Zoo, the city's mayor Honey Lacuna announced during a news conference on Wednesday. The Asian elephant earned the moniker because she was the only captive elephant in the Philippines and lived alone at the zoo for decades, according to animal rights group People for the Ethical Treatment of Animals, which has advocated for Mali.

Mali lived at the zoo for about 45 years and caught the attention of Paul McCartney in 2013 when he worked with PETA to raise awareness for the elephant and penned a letter to Philippine President Benigno Aquino III urging the transfer of Mali to an elephant sanctuary in Thailand.

At the time, PETA U.K. said Mali "endures intense confinement, loneliness, boredom and isolation" in an area that is a fraction of the size of her natural habitat.

An elephant sanctuary in Thailand was prepared to take Mali in, according to PETA U.K., but she stayed in Manila, where she was the main attraction at the zoo. 

Other celebrities, including Pamela Anderson and Jane Goodall joined the effort to "free Mali."

At the end of her life, Mali had cancer and was seen rubbing her trunk against a wall, meaning she was in pain, Dr. Heinrich Patrick Peña-Domingo, the chief veterinarian a the zoo, said at the news conference, according to BBC News. Vets gave her antihistamines and vitamins when she was breathing heavily on Tuesday, but she died later that day.

While animal rights activists advocated for Mali to be moved from her isolated home, the zoo argued it was the only place she had known and that vets were providing her with care, BBC News reported.

Mali was transferred to the zoo from Sri Lanka and following her death, PETA Asia urged the country not to send another one of its animals to Manila. 

In a statement to CBS News, PETA Asia said Mali, who was nearly 50, died in her "barren concrete pen," because of "indifference and greed." The animal rights organization said living in what called solitary confinement is "torture" for female elephants because they naturally spend their lives alongside other female elephants and work together to raise their babies. 

"Despite PETA's repeated warnings, zoo and city officials ignored Mali's clearly painful foot problems, sentencing her to years of suffering," PETA Asia's statement reads. "The Manila Zoo has announced that Mali had cancer that was not detected by their veterinarians until after she died. Due to the fact that there is no elephant expert in the country, Mali was never provided with routine veterinary care—something she would have been given at the sanctuary PETA was prepared to transfer her to."

PETA Asia said those who denied Mali proper care and a different home "should be held accountable for their part in allowing Mali's suffering." 

CBS News has reached out to the Manila Zoo and is awaiting response. 

According to U.K.-based conservation charity People's Trust for Endangerd Species, Asian elephants, who are smaller than their African cousins, have an average lifespan of about 70 years in the wild — in captivity, it's about 80 years. The oldest Asian elephant in captivity died in 2019 in India at 88 years old, according to a piece credited to the group for BBC Wildlife Magazine. 

The Smithsonian National Zoo, however, says despite consistent data, evidence suggests Asian elephants typically live into their mid-50s and median life expectancy for female Asian elephants is 47 years old.