Story highlights Tenzin Delek Rinpoche has died, according to the Tibetan government-in-exile

He was serving a life sentence in a Chinese prison

U.S. State Department calls for his death to be investigated

Hong Kong (CNN) A prominent Tibetan monk has died in a Chinese prison in Sichuan province, according to the Tibetan government-in-exile.

Tenzin Delek Rinpoche was serving a life sentence, according to the Central Tibetan Administration, which operates out of the Indian city of Dharamsala.

In 2002, he had been found guilty of setting off explosions and inciting separation of the state, according to Xinhua, China's state-run news agency.

"We are very sad; it's shocking news for us. He has been a very prominent religious teacher. His case has been brought up internationally for years," Tashi Phuntsok, spokesperson for the Central Tibetan Administration, said.

He had initially been sentenced to death but it was commuted to life in prison in 2005.

Read More