Little is now known about Liu, 56, and his current condition - he is said to suffer from hepatitis - due to a curtain of silence drawn across him and his family by China's government, which was deeply embarrassed by the award and reacted angrily.
This makes it difficult to confirm whether Liu is even still at the prison in Liaoning province in northeastern China where he was initially jailed.
Liu's wife Liu Xia, remains under house arrest at their home in Beijing to prevent her speaking about her husband's case, while his brothers continue to decline media interviews.
"I don't have any information about Liu Xiaobo and I have been unable to reach Liu Xia," Dai Qing, a fellow activist who is close to the couple, told AFP.
Liu, who was jailed previously for his involvement in the 1989 Tiananmen pro-democracy protests, was sentenced in 2009 to 11 years in jail for "attempted subversion of power" after co-authoring a bold manifesto for democracy in China.