Seoul Zoo confirmed on Monday the unexpected death of Suho, one of their resident Siberian tigers. At just 10 years old, Suho's death came a decade earlier than the typical 20-year life expectancy for Siberian tigers, a critically endangered species.

Suho was found unresponsive during viewing hours in the zoo's exhibition hall in Seoul Grand Park, Gwacheon on Sunday. Despite immediate efforts to revive him, he was pronounced dead soon thereafter.

With the continued heat wave pushing daily high temperatures above 35 degrees Celsius, speculations have emerged that Suho might have died of heatstroke. Questions were raised about the lack of air conditioning and protection from the sun in the exhibition hall, where Suho was at the time, especially given the oppressive heat.

In response, zoo officials claimed that the tiger’s enclosure has adequate shade and water. They added, rather pragmatically, that Siberian tigers have short hair in the summer so are able to regulate their body temperature on their own.

This isn't the first death of a Siberian tiger at the zoo this year. Last May, Parang, at just one year old, passed away after contracting the feline panleukopenia virus.

The exact circumstances surrounding Suho's sudden death remain under investigation.