Liu Xiaobo, the renowned Chinese activist who was imprisoned for holding a pro-democracy vigil at Tiananmen Square in 1989, and was ultimately awarded the Nobel Peace Prize for his efforts, died under guard at a Chinese hospital this week. He was 61 years old, The New York Times reports.

The Chinese government publicly revealed Liu was suffering from liver cancer in late June, only after his case was virtually beyond treatment. Earlier this summer, Lui was technically granted medical parole to obtain treatment for this condition, however, he was denied multiple requests to leave China to seek treatment abroad for his deteriorating health.

On July 10, hospital officials announced Liu had gone into critical condition, and detailed the deterioration of his heath, saying he was no longer a suitable candidate of invasive procedures or radiation. On July 13, the pro-democracy activist died due to multiple organ failure after several attempts were made to save his life.

Shortly before his death, two Western doctors visited Liu and his family and requested that the remainder of his care be provided in Germany or the United States. However, the Chinese government ultimately denied this request.

Liu was arrested most recently in 2008, after he helped initiate a bold petition calling for democracy, the rule of law and an end to censorship in China. A year later, a court in Beijing tried and convicted Liu on a charge of “inciting subversion.”  He had been serving an 11-year prison sentence at the time of his death.

The dissident’s plight has come under a global spotlight amid allegations from his supporters that Liu fell gravely ill because his cancer was not detected or treated while he was in prison. Prison authorities said Liu, who also had a history with the hepatitis B virus (HBV) received monthly check-ups and had “no abnormal conditions” before the liver cancer diagnosis.