Mr Wangchen spent five months interviewing Tibetans about their hopes and frustrations living under Chinese rule. After the footage was smuggled abroad and distributed on the Internet, and at film festivals around the world, he faced charges of state subversion.
Mr Wangchen's family hired lawyer Li Dunyong to defend their relative, but he was barred from court last July. Before he was forced to drop the case, he said Mr Wangchen had told him that he was tortured and that he had contracted hepatitis B while in custody. Since then, he has been held incommunicado.
A month ago, Mr Wangchen managed to smuggle a letter out of prison to a cousin in Switzerland. America's New York Times publicized the case. "There is no good news I can share with you," Mr Wangchen wrote. "It is unclear what the sentence will be."
Mr Wangchen's wife Lhamo Tso told us that the worldwide publicity generated by the New York Times article is a good thing and is useful for putting pressure on the Chinese government. She added that international journalists have given her husband much support, and she hopes this will continue.
Lhamo Tso said that under tight prison security her husband did remarkably well to smuggle the letter out, and that he is very worried about his family in India - Lhamo Tso fled to Dharamsala with their four children just before her husband began filming.
As US President Obama prepares for his first trip to China next month, human rights advocates are seeking his attention, in hopes that he will raise the plight of individuals like Mr Wangchen and broach topics such as free speech, democracy and greater religious freedom.
Lhamo Tso told us that President Obama is widely seen as a champion of peace and that she hopes he will work on the Tibetan issue whilst in office. "My husband is in prison. I ask that when President Obama meets Chinese President Hu Jintao he will discuss my husband's case, as a human being."