In the long term, experts say, it may even be possible for the Communist government to feed images produced from a DNA sample into the mass surveillance and facial recognition systems that it is building, tightening its grip on society by improving its ability to track dissidents and protesters as well as criminals.

Some of this research is taking place in labs run by China’s Ministry of Public Security, and at least two Chinese scientists working with the ministry on the technology have received funding from respected institutions in Europe. International scientific journals have published their findings without examining the origin of the DNA used in the studies or vetting the ethical questions raised by collecting such samples in Xinjiang.

In papers, the Chinese scientists said they followed norms set by international associations of scientists, which would require that the men in Tumxuk (pronounced TUM-shook) gave their blood willingly. But in Xinjiang, many people have no choice. The government collects samples under the veneer of a mandatory health checkup program, according to Uighurs who have fled the country. Those placed in internment camps — two of which are in Tumxuk — also have little choice.