Technology a game-changer in solving China’s cold cases

NANJING — A man’s decomposed body parts were found in an open space in Kunshan, Jiangsu province, in December 2011.

Police collected DNA samples at the scene, hoping the evidence would unlock the secret of the man’s identity, but the investigation stalled over a lack of technology.

Thanks to facial recognition software, police came up with a possible identity last year and compared the DNA samples with the people thought to be his parents. It was a match.

Officers were then able to catch the murderer, who had killed the man during a dispute over how to divide the gains from credit card fraud.

The software analyzes aspects of a person’s face — the space between the eyes or how long the nose is — and creates a template, which is then compared with photographs in a database.

“The technology is not affected by changes in physical appearance such as hair style and body shape,” said an investigator involved in the case who asked not to be named.

“The process of photo matching, when done manually, is hugely time consuming. Police now can devote more time to other vital tasks,” he said.

Technology has become a game-changer for unsolved cases, especially ones that have long gone cold. It can greatly increase the efficiency of police officers.

Chinese police launched a campaign in 2016 to use new technology to solve cold cases. Last year, 41 cases were solved in Jiangsu, with the earliest crime committed 30 years ago. There were 29 crimes solved in 2016, and 19 in 2015, the provincial public security department said last week.

In Zhejiang province, all murders committed in 2017 were solved before the end of the year. Police also solved 88 cold cases, around 70 percent of them using fingerprints, DNA or facial recognition technology.

Crime shows on television may lead audiences to believe that DNA samples can easily convict the guilty and clear the innocent, but in real life it is more complicated.

The DNA has to match either a previous offender in the national law enforcement database or a sample from one of the victim’s close relatives. When it does not, the investigation hits a wall.

A 58-year-old man, surnamed Xu, was caught by police in March, 20 years after he killed a prostitute in Lianyungang, Jiangsu, in a dispute over the fee he should pay her.

DNA use in criminal cases was still in its infancy in the 1990s. When officers of the Lianyungang police set up their first DNA testing laboratory in 2004, investigators compared Xu’s DNA profile with certain offenders in the national law enforcement database.

It did not lead to a match until recently, when Xu committed another crime and his DNA sample was recorded in the database.