Critics say Beijing is exploiting the openness of the international scientific community to harness research into the human genome for questionable purposes. The Chinese have said that they followed international norms that would require research subjects’ consent, but many in Xinjiang have no choice.

And Times reporters were prevented from interviewing residents of Tumxuk, the site of two internment camps, making it impossible to verify consent.

Scope: The police in China turned to Chinese scientists with connections to leading institutions in Europe, which sometimes funded their work. The process, called DNA phenotyping, is also being developed in the U.S. and elsewhere.

Quotable: The Chinese government is building “essentially technologies used for hunting people,” said one professor who tracks Chinese interest in these technologies.

Inside the reporting: Sui-Lee Wee, one of the two reporters on the story, said officials in Tumxuk went to extreme lengths to stop the reporting. “The cops deleted all the photos and videos from our phones,” she wrote on Twitter, “and asked for the passwords to our social media accounts.”