A last-minute booking, a furtive cab ride and a spy in the window. For the past year, Paul Mozur has been investigating the story of a son determined to free his mother from a repressive system of detention and surveillance in western China. In doing so, he found a crack in China’s surveillance state — and a mother on her deathbed in Xinjiang. Today, we hear from the man’s mother for the first time.  Guest: Paul Mozur, a technology reporter for The New York Times based in Shanghai, spoke with Ferkat Jawdat, a Uighur who is an American citizen and lives in Virginia, and his mother in Xinjiang, China. For more information on today’s episode, visit nytimes.com/thedaily.  Background reading:The Chinese authorities are using a vast secret system of facial recognition technology to control the Uighurs, a largely Muslim minority in western China. The government may also be taking citizens’ DNA without consent to enhance the system.“We must be as harsh as them, and show absolutely no mercy.” Leaked documents reveal how the Chinese authorities orchestrated the crackdown on one million or more ethnic Uighurs.If you missed our previous interviews with Mr. Jawdat, here are Part 1 and Part 2.