Nevertheless, Shawn Zhang, a 29-year-old Chinese law student in Canada, has been playing an important role alongside scholars such as Zenz and Grose. Like them, he began hunting for information on what was happening in Xinjiang by searching the internet for “reeducation center” using Baidu and Google. He, too, noticed the construction bids, many of which specified where the camps were to be built. Then he took an additional step: He plugged the location information into Google Earth—and found satellite imagery of what appeared to be camps.

Zhang told me he started doing this in May after reading news reports saying hundreds of thousands of Muslims were being sent to Chinese camps: “When I saw the news, I was skeptical. I thought, how is it possible to detain so many Uighurs? … How is it possible for this kind of thing to happen in 2018? So I decided to check out this information myself.”

Seeing the satellite imagery convinced him that it really was possible that Muslims were being detained en masse in his native country—and that some of the camps kept growing, month after month. He started posting the images on his blog and his Twitter account, along with the coordinates of the facilities, so that anybody could examine them. This project, to which he said he devoted an hour of free time each day on average, soon attracted the attention of professional journalists and scholars. They began to collaborate.

Zhang said journalists on the ground in Xinjiang have asked him for help identifying potential internment camps: “They sometimes ask me if I can give them some camps that are more accessible, easier to visit, so they can visit them onsite.” An important Wall Street Journal investigation, which involved a visit to a camp in the city of Turpan, made use of Zhang’s work. The Journal reporter Josh Chin confirmed to me that he’d asked Zhang to help analyze photos and satellite images of the Turpan site to see if its characteristics resembled the characteristics of other sites Zhang had cataloged as camps. The features did match, and in fact, Zhang said, he had already found the Turpan site via Google Earth and surmised that it was a camp.

Explaining why he hadn’t posted the details of that camp online, Zhang told me that he sometimes finds a structure that he thinks looks like it may be an internment camp, but he avoids publicly identifying it as such unless he can verify it. In the Turpan case, he said, “I didn’t post it on my blog, because I didn’t have corroborating evidence. I need to find at least one [piece of] corroborating evidence, like a tender notice or some local news, before posting it.”

Zhang said internment camps have telltale visual hallmarks that help distinguish them from other facilities he can identify from government tender notices and construction bids as regular prisons, detention centers, or schools. For instance, he said, detention centers are typically one or two stories high and have very little yard space, unlike the camps, which tend to have at least three or four stories and occupy sprawling grounds. Nevertheless, it can be difficult to say with certainty that a facility viewed only through satellite imagery is a camp, which is why scholars, journalists, and Zhang himself try to supplement that approach with other methods of verification.