A group of leading international human rights specialists urged the United Nations on Thursday to help find one of China’s top Christian human rights lawyers.

Gao Zhisheng, who was once named by the Chinese government as one of the country’s ten best lawyers, has been missing for one year as of Thursday. He was reportedly seized by a dozen police officers and last seen in public on Feb. 4, 2009. The Chinese government has made vague references to Gao’s detainment, but many times it has also denied knowing where he is.

“We urge China to let Gao Zhisheng’s family know where he is being held and why he is being detained, in accordance with Chinese law,” said Jerome Cohen, a professor at New York University Law School and one of the nation’s foremost expert in Chinese law. “He should immediately be granted access to council and either charged with a crime or released.”

Cohen has partnered with Irwin Cotler, a Canadian Member of Parliament and its former Minister of Justice and Attorney General; David Matas, a distinguished human rights lawyer; David Kilgour, a former Canadian Member of Parliament; and Freedom Now to file a petition with the U.N. Working Group on Involuntary Disappearances.

Cotler served as a counsel to Nelson Mandela, among other notable political prisoners.

In the petition, the rights specialists inform the U.N. working group of the violations of criminal procedure in Gao’s case and request immediate assistance from the United Nations to locate Gao.

“Freedom Now's long track record of successful interventions filed with the United Nations ensures that the international community will remain relentless in securing Mr. Gao's release,” said Ann Buwalda, executive director of the faith-based rights organization Jubilee Campaign, in response to the U.N. petition.

Since December 2009, rumors have circulated that Gao is dead. Earlier reports say he was beaten and tortured. Chinese officials have simply said he is “missing” from their custody or “where he should be,” without further details given.

Gao became a target of government persecution after he took on politically sensitive cases related to police corruption, land seizures, and religious freedom, including defending house church Christians. Gao himself is a Christian and attends a house church.

In 2007, Chinese authorities imprisoned Gao and severely tortured him. He was released and told never to disclose what happened while he was in prison. After his disappearance, Gao’s wife, Geng He, released an open letter by her husband detailing the torture he suffered while in prison.

Geng, who is now living in New York after fleeing China, says her husband is being persecuted “for giving a voice to those that China wished to silence.”

“I can only hope that his lawyers can do for him what he was able to do for so many,” she stated.

In 2008, Gao was nominated for the Nobel Peace Prize. This week, a bipartisan group of U.S. Congressmen nominated Gao, along with Attorney Chen Guangchen and political activist Liu Ziaobo for the 2011 Nobel Peace Prize.