Although few people have heard of the "tech police", the squad's officers are there for the people, keeping an eye on their safety via technology, said Zhang Qi, captain of the video squad at the Tongzhou branch of the Beijing Public Security Bureau.

The 40-year-old said such units use scientific and technological information to fight crime, solve cases and search for clues hidden in complex information.

Having dreamed of becoming a police officer since childhood, Zhang was admitted to the People's Public Security University of China in 2003, majoring in crime detection via computer science. After graduating in 2007, he joined the Science and Technology Information Department of the Tongzhou branch.

However, he was "blindsided" on his first day at work when he was put in charge of basic network communications, which was a far cry from his idea of "science and technology information".

The complex network exchange commands and structure confused him, so he had to start from scratch. After months of study and practice, he gained a comprehensive understanding of the work.

"Everything is changing so fast in my field that if you don't study for a month, you risk being overwhelmed by the wave of fast-moving technology," he said.

In 2014, the unit started building community stations that focused on sci-tech information. Zhang led the team in driving hundreds of kilometers every day through streets, villages and communities to grasp the daily work of local police stations and understand the use of science and modern technology.

"Traditional methods can no longer deal with modern developments," he said. "We must have a more detailed understanding of the actual work of the police so our information technology can serve the public well."

He and his colleagues also incorporated the experiences of former officers into the data model and spent about a month completing the basic construction of 152 new-style stations.

In 2015, Tongzhou was designated as Beijing's new administrative center. With Zhang leading the work, his unit started planning how to use science and technology to support the overall construction of the civic center.

To ensure quality and efficiency, Zhang and his colleagues lived in their office, spending three months completing the planning, which provided support for the implementation of more than 30 scientific and technological projects in the center.

In 2019, the deepening of public security reform saw the branch establish a team to focus on intelligent police applications.

The officers, Zhang included, summarized investigative techniques with strong applicability in similar cases, built a matrix system covering 42 types of investigative methods and refined "formulas" for case investigations.

He said the technology police system is like a modern internet company, which has no history or baggage to hold it back. Meanwhile, the public security department can make good use of advanced technologies to improve the efficiency of case-solving efforts.

While processing long-pending cases, the team caught a suspect who had been on the run for 21 years just by using an old black-and-white photograph.

They found the photo as they searched through a large number of historical materials, so they used new technology to make a verification via 100 similar snaps.

During the past two years, the Tongzhou branch has assisted in the investigation of more than 3,000 cases through science and technology, integrating new techniques into their case-handling process.

"What I have felt most since becoming a police officer is that we never have a real break. We need to be on the job 24 hours a day in case of developments or emergencies," Zhang said.

In his 15 years with the force, Zhang has never spent New Year's Eve at home. He planned to take leave to visit his mother for Spring Festival in 2020, as his father had died just a few months before. However, the COVID-19 outbreak meant he had to stay at his post.

In just a few days, he and his colleagues built more than 20 epidemic prevention and control data models and immediately applied them to the front line.

"As 'tech police', we use the power of science and technology to serve the people's interests and guard them," Zhang said.