The great and fearsome Tilikum, the world’s most famous killer whale, is near the end of his tragedy-filled life.

On Tuesday, SeaWorld Orlando in Florida, where Tilikum has lived for the past 23 years, issued a statement announcing that the 12,000-pound orca is suffering from an untreatable lung infection.

The killer whale gained global notoriety in February 2010 when he dragged trainer Dawn Brancheau into his pool and brutally rammed her to death. She was the third person killed by Tilikum.

“We are saddened to report that over the past few weeks, Tilikum's behavior has become increasingly lethargic, and the SeaWorld veterinary and animal care teams are concerned that his health is beginning to deteriorate,” the statement said.

“Our teams are treating him with care and medication for what we believe is a bacterial infection in his lungs,” the statement continued. “However, the suspected bacteria is very resistant to treatment and a cure for his illness has not been found.”

In a video released with the statement, SeaWorld veterinarian Scott Gearhart, teary-eyed, addressed the camera.

“I wish I could say I was tremendously optimistic about Tilikum and his future, but he has a disease which is chronic and progressive and at some point might cause his death,” Gearhart said. “We have not found a cure for this disease at this point.”

Heather Murphy, an anti-captivity activist from central Florida and cofounder of Ocean Advocate News, went to see Tilikum on Tuesday.

“He was in the med pool, and he was barely moving,” Murphy said. “The entire time I was there, he stayed at the gate looking out. There were other whales hanging out at the gate with him on the other side. It’s all very sad.”

Tilikum is thought to be about 35. The average life expectancy for wild male orcas is about 30. He was captured and taken from his mother’s side off the coast of Iceland in 1983, when he was about two.

Brancheau’s death led to an international outcry against killer whale captivity, sparked a six-month investigation by the United States Occupational Safety and Health Administration, and led to a protracted legal battle in which SeaWorld unsuccessfully tried to have the worker-safety violation overturned.

Since then, Tilikum and SeaWorld have been the subject of my book, Death at SeaWorld, the 2013 documentary Blackfish, and a cascade of devastating publicity that resulted in tanking stock values, high-level-staff departures, and the introduction of a bill to ban orca captivity in California.

Brancheau was not the first person to fall victim to Tilikum’s fury. In 1991, when the orca was living at the now-defunct SeaLand of the Pacific in Victoria, British Columbia, he pulled trainer Keltie Byrne into the water and, along with two female orcas in the pool, prevented the champion swimmer from escaping until she drowned.

The whale was sold to SeaWorld Orlando in 1992. Seven years later, a homeless man named Daniel Dukes was found naked, dead, and draped over Tilikum’s back after sneaking into his pool after the park closed.

Becca Bides, SeaWorld director of corporate communications, declined to answer several email questions about Tilikum, including the type of bacteria that has infected him, whether or not he is eating, and how long he might have to live.

In the video, Gearhart said that Tilikum is infected with “a type of bacteria that is found in a variety of species, including wild cetaceans,” without naming the pathogen. “If Tilikum had shown up with this disease in the wild, he would’ve been gone a long time ago.”

But Naomi Rose, a killer whale expert and marine-mammal scientist at the Animal Welfare Institute, took issue with that statement.

“Talk about speculation and going way beyond the data,” Rose said. “You don’t know if he would’ve had this disease in the wild—it’s nonsensical. SeaWorld is trying to say, ‘Look how long we kept him around.’ But how do you know he would be in this predicament if he wasn’t in captivity?”

Rose said that wild whales die from bacterial infections, but without disclosing the pathogen affecting Tilikum, Gearhart’s statement “is absolutely meaningless.”

Lori Marino, executive director of the Kimmela Center for Animal Advocacy and a neurobiologist who has studied whales and dolphins for 25 years, said the stress of being held in a tank for most of his life could have led to Tilikum’s illness.

“There is a well-known syndrome of how chronic stress affects the immune system and how that leads to infection and mortality,” Marino said. “Chronic stress, including depression, essentially releases chronic stress hormones into the body, degrading the immune system, which leads to increased vulnerability to infection.”

We may never know what will kill Tilikum. SeaWorld is not required to release necropsy reports for its animals.

But the orca’s legacy will outlive the animal.

“We knew this was coming, but that doesn’t make this any easier,” Marino said. “It’s a sad ending to a sad story.”

This article originally appeared on TakePart.com. Reprinted with permission. [[{“type”:”media”,”view_mode”:”media_small”,”fid”:”604699″,”attributes”:{“alt”:””,”class”:”media-image”,”style”:”height: 35px; width: 150px;”,”typeof”:”foaf:Image”}}]]

YOU MIGHT ALSO LIKE

SeaWorld to End Killer Whale Shows in Wake of Mounting Protests

Star of 'Jackass' Movie Franchise Arrested for Anti-SeaWorld Stunt in Hollywood

SeaWorld Sees Profits Plunge 84% as Customers Desert Controversial Park