In August 2009, Ai Weiwei traveled to Chengdu, China, to testify on behalf of Tan Zuoren, an activist arrested and charged for his activities in researching the student deaths from the Sichuan earthquake. Ai was in his hotel room when police officers forced their way in and beat him. Ai was prevented from attending the trial and from testifying. Ai complained of pain from the beating he suffered and the police agreed to allow him to go to the hospital. On the way out of the hotel, Ai noticed the mirrored surface of the elevator and quickly snapped a photograph on his cell phone. This image would later be shared online, alerting Ai’s supporters of what had transpired in Chengdu.