Human Rights Watch on Thursday urged China to free the 11th Panchen Lama, Gendun Choki Nyima, and his parents, who were removed from public view in 1995 and have remained missing ever since. As the 30th anniversary of their disappearance approaches on Saturday, human rights advocates have intensified pressure on Beijing to end decades of secrecy and take accountability for the Panchen Lama and his family.

There is still some doubt over whether Nyima, who disappeared at the age of six, is alive—despite an unsubstantiated claim in 2015 from Chinese authorities that “this so-called ‘soul boy’ designated by the Dalai Lama is receiving education, living normally and growing healthily. He does not want to be disturbed by anyone.”

The Panchen Lama is one of the most important figures in Tibetan Buddhism, with his spiritual authority second only to the Dalai Lama. The Dalai Lama himself is believed to be the reincarnation of a long line of compassionate teachers who choose to be reborn to help others. After the Panchen Lama was taken, Chinese authorities allegedly engaged in an illegal method of choosing his replacement that ran contrary to the values of Tibetan Buddhism. The authorities ultimately selected Gyaltsen Norbu, whose parents were members of the Chinese Communist Party (CCP).

Norbu’s appointment is alleged to be a tool for the Chinese government to exert control over the religious and cultural traditions of Tibetan Buddhism, particularly to assert state power over spiritual accession. The majority of Tibetan Buddhists reject Norbu’s appointment, branding it an abuse of human rights.

The Chinese government’s intervention in religious circles in Tibet has been alleged to be a part of a broader wave of Sinicization—i.e., an effort to completely subordinate groups to the CCP’s political agenda and Marxist vision for religion. In addition to controlling the selection of the Panchen Lama, Chinese authorities have been accused of committing gross violations of religious freedom against the Tibetan Buddhist community over the years. According to HRW, monks have been forced to undergo political reeducation, religious imagery, texts and statues have been forcibly altered in Buddhist shrines, and Tibetan children have been forcibly assimilated to the majority Hans culture in a fashion that is eerily similar to the residential school system imposed on Indigenous Canadians until as late as 1996. Tibetan children have also allegedly been prohibited from attending Tibetan language classes in local monasteries, with the Chinese government describing the classes as “ideological infiltration among the young.”

The alleged persecution of Tibetan Buddhists is believed to stem from China’s aim to promote national unity by destroying the very foundations of the religion from the top down. With the Dalai Lama turning 90 in July, it is expected that the Chinese government will also interfere in the process of choosing his successor. The Dalai Lama has been living in exile in North India since 1959 after a failed uprising against Chinese forces.

HRW has urged countries with significant Buddhist populations, such as Korea, Mongolia, Taiwan, and India, to speak out and step up international pressure on China to return the Panchen Lama.