A conservation group in South Africa accidentally killed a rhinoceros Thursday during an anti-poaching demonstration performed in front of a group of reporters.

The demo required that Spencer, a male rhino in his late 20s, be shot with a tranquilizer gun so that demonstrators could dye and insert a tracking device into his horn—a procedure meant to deter poachers from slaying the animal for its horn. But the sedation process failed.

"The rhino had an unfortunate reaction to the anesthesia," Lorinda Hern, a spokeswoman for the Rhino & Lion Nature Reserve told Reuters. "Every time you dart a rhino, you take a risk that the rhino might not wake up and unfortunately today was one of those days."

The animal reportedly went into convulsions and could not be revived.

Joseph Okori, a veterinarian and World Wildlife Fund rhino expert who witnessed the botched procedure, told the Washington Post that of the 50 rhinos he has sedated over the last fifteen years, just one has died.

"There is always a potential risk," he said. "The whole issue is, we are facing a serious rhino poaching crisis. This is a war. The desperation is quite high for rhino owners, to do whatever it takes to protect their rhinos."

In 2011, a record 488 rhinos were poached from South Africa, according to the Post. Rhino horns are believed by some Asians to have medicinal properties and can go for about $6,500 a kilogram on the black-market (more expensive than gold or platinum).

Hern told the Post that Spencer's death would not deter the reserve from continuing to treat rhino horns. His death, attributed partly to his age, was the first among up to 20 other rhinos who had undergone the same treatment.