Wang Lei, a member of criminal investigation department of Beijing police, squats beside the tombstone of police dog "Benben" on June 23, 2014. The police dog division of Beijing Municipal Public Security Bureau was founded in 1952. Up to 2015, there have been more than 1,000 police dogs serving in criminal investigation, SWAT, public transportation, firefighting and some other departments of Beijing police. (Xinhua/Sui Xianghua)