BEIJING >> The wife of one of China’s most prominent human rights campaigners said Thursday that he had disappeared during a trip to visit relatives of a detained rights lawyer.

Jiang Tianyong, a legal activist, has not been heard from since Monday, when he was due to board a train to return to Beijing, according to his wife, Jin Bianling.

Jiang’s defense work involved some of China’s most politically sensitive figures in recent years, including the dissident lawyer Gao Zhisheng and blind activist Chen Guangcheng.

Jiang was disbarred in 2009 but has continued his activism, recently helping to publicize the plight of nearly two dozen lawyers arrested as part of a sweeping 2015 government crackdown. Jiang met with relatives of one of the jailed lawyers in Changsha in central China shortly before going missing.

He could not be reached on Thursday by his mobile phone, which was turned off.

Jiang told the Associated Press in June that he feared he could be detained at any moment and rarely spent more than a few nights in one place.

Speaking by telephone from California, Jin said her husband’s family sought to file a missing person report in his city of registered residence, Zhengzhou, in central China but police turned them away and told to seek information in Beijing instead.

The Ministry of Public Security in Beijing did not immediately respond to a fax requesting comment about Jiang’s whereabouts.