A man in his 60s, medium height, and a little thin. That was all Zhang Xin needed to know when he was composing the portrait of the suspect who caused an explosion in Linfen, Shanxi province, in 2014.
Known as the "Magical Pen", Zhang was a senior sergeant of criminal investigation at the Shanghai Railway Public Security Bureau and an expert in facial composites. Over a career of more than 30 years, he helped solve more than 800 cases by sketching suspects' faces based on vague descriptions.
The bureau announced Zhang had died in a post on social media on Oct 21. He was 58 years old, and the cause of death was given as extreme exhaustion.
Zhang became a police officer in 1982, and at the time painting was just a hobby. He was first asked to sketch a suspect portrait in 1986, which helped his colleagues solve a theft case. From then on, he was transferred to the bureau's criminal technology team.
To improve his skills, Zhang took advantage of every minute of his daily train commute to and from work to sketch the facial features of the people around him. In all, he drew more than 10,000 sketches.
He also attended art college and spent his holidays traveling in cities and villages as well as visiting ethnic communities to observe the diverse physical features of the locals. After sketching tens of thousands of pictures for various cases, he began to earn a reputation. "The more challenging the case, the more motivated I become," he told China Central Television in an interview.
The job required Zhang to have ample experience and be extremely logical, as witnesses tend to describe things emotionally after experiencing psychological trauma.
He recalled in the CCTV interview a rape victim who had told him that her attacker had "extremely round eyes". Zhang had held up a coin and asked her if the eyes were as round as the coin, and she said the rapist's were even rounder.
"That was impossible. It was definitely an exaggeration," he said.
Zhang was best known for sketching the facial composite of Gao Chengyong, one of China's most notorious serial killers, who murdered 10 women and an 8-year-old girl between 1988 and 2002 across northern China.
He was asked to join the investigation to sketch the suspect's face in 2002. A year earlier, the killer attempted to assault a female factory worker, which resulted in three witnesses: the victim, her husband, and a police officer who passed the suspect en route to the scene.
Zhang later said that he had never experienced such difficulty before, as a whole year had already passed and their memories had faded.
"Due to the significance of the case, I had to carefully sift through each piece of information from their descriptions and sort out the most useful ones," he said. Even though the descriptions were vague and subjective, Zhang said there was scientific logic, such as a fat person cannot have a thin nose.
He spent three days sketching three pictures of the suspect, which provided a lead for detectives to eventually track down the murderer.
After the announcement of Zhang's death, the bureau paid tribute by honoring his achievements. "Zhang Xin fought on the front line to solve crime," it said on social media. "The hero has gone, but the spirit remains. May our compatriot rest in peace."