Chinese photographer Lu Guang spent nearly 40 years documenting the effects of environmental destruction in rural and industrial regions of China. Then, in November, he disappeared.

Lu, who lives with his family in New York, returned to China to lead a photography workshop in late October. The region he was visiting, Xinjiang, is the location of detention sites holding hundreds of thousands of Muslim prisoners. About a month and a half after his disappearance the Chinese police informed Lu’s family that he had been arrested, his wife told the New York Times.

Forty-seven journalists are known to be imprisoned in China as of the end of 2018, says Steven Butler, the Asia program coordinator for the Committee to Protect Journalists