 Gutmann conducted extensive interviews around with former detainees in Chinese labor camps and prisons, as well as former security officers and medical professionals with knowledge of China's transplant practices.He reported that organ harvesting from political prisoners likely began in Xinjiang province in the 1990s, and then spread nationwide.Gutmann estimates that some 64,000 Falun Gong prisoners may have been killed for their organs between 2000 and 2008.