A decade ago, a six-year-old boy was named by the Dalai Lama as a spiritual leader of Tibetan Buddhism.
Gedhun Choekyi Nyima is still the Dalai Lama's choice
Gedhun Choekyi Nyima was nominated as the reincarnation of the Panchen Lama - the second-most important figure in Tibetan religion, culture and politics after the Dalai Lama himself.
But China disagreed with the choice and arrested the boy a few days later.
Mystery surrounds his fate and outside China he is known as one of the world's youngest political prisoners.
China installed their own boy, Gyaincain Norbu, as the true 11th reincarnation of the Panchen Lama.
Campaigners say the child chosen by the Dalai Lama is held under house arrest somewhere in China, but details remain unknown.
Tibet's exiled leaders refuse to accept China's choice and call for Gedhun Choekyi Nyima to be released.
Historian Tsering Shakya of Oxford University said: "He virtually disappeared and the Chinese government took him under what they call protective custody."
Most Tibetans, experts say, wholeheartedly rejected the Chinese-chosen Panchen Lama.
Arjia Rinpoche, the abbot of Tibet's important Kumbum monastery now living in exile in the US, said the Dalai Lama's choice held sway with Tibetans.
"The Communist government still wants to promote their version of the Panchen Lama but 90% of the Tibetan people, they don't believe," he said.
The pictures displayed on the altar in Tibet's most celebrated temple - the Jokhang - are not those of China's choice for the 11th Panchen Lama.
Gyaincain Norbu has Beijing's backing as the Panchen Lama
Instead worshippers look at images of the face of the 10th Panchen Lama.
In public, they are too scared to explain why. But, in secret, they admit that no-one believes in Beijing's boy and many see him simply as a puppet of the Chinese state.
Government authorities are full of praise for the official Panchen Lama, describing him as clever, sharp and well-mannered.
State television broadcasts pictures of him dressed in his distinctive orange robes, being escorted into temples under the cover of darkness.
The crisis sparked by the disappearance of Gedhun Choekyi Nyima has now reverberated through the Tibetan Buddhist community for a decade.
But, according to Tsering Shakya, a bigger crisis awaits the community. That will be sparked by the death of the Dalai Lama, now in his 60s.
Traditionally the Panchen Lama is key to recognising the reincarnation of the Dalai Lama.
Tsering Shakya said: "I think the Chinese government will try to go ahead and try to appoint their own candidate through the Panchen Lama."
Meanwhile the crisis has already claimed some very real victims, our correspondent says - both the boy groomed by Beijing but repudiated by his followers, and his counterpart, the young man judged as such a threat to Chinese control in Tibet that he was taken from view a decade ago.