IN crime novels, police detectives often solve mysteries by intuition. Zhang Baofa would say that’s pretty fanciful fiction.

Zhang, 58, is the chief officer of the Technical Investigation Department of the Shanghai Public Security Bureau. It’s his job to use scientific and technological methods to search for clues, identify suspects and arrest perpetrators.

In Zhang’s 25-year technical investigation career, he and his team have been involved in many high-profile cases, including the hammer assaults and robberies of 14 women in 1997, the Juneyao milk poisoning case in 2000 and an international diamond theft in 2004.