Although her youngest son died while performing his police duties last year, the sorrow and pain of losing him haven't stopped Peng Taizhen supporting her other two sons'work as police officers.

However, it wasn't the first time Peng, from Lincang, Yunnan province, had lost a loved one in the line of duty. Her husband Zhang Congshun, the head of Junnong Police Station in Gengma county, Lincang, was killed while fighting drug runners.

As a border city, Lincang faces the challenge of an influx of illicit drugs from the Golden Triangle－where Thailand, Laos and Myanmar meet－and other illegal activities.

In 1994, Zhang was involved in a confrontation with an armed cross-border drug gang. One of the gang members detonated a grenade during the fight. Zhang, who was trying to save a colleague, was seriously injured and later died of blood loss.

"My husband died, leaving many unfinished things in crime fighting behind him. But we still have sons to continue along the path. If I had the chance to choose again, I would still support them," Peng said.

Her deceased son Zhang Ziquan was an anti-drug police officer at the Lincang municipal public security bureau. The 36-year-old died while investigating a cross-border people smuggling case.

On April 1, the Publicity Department of the Yunnan Provincial Committee of the Communist Party of China posthumously bestowed the "Yunling Model" title on both father and son for their outstanding work performances.

One of Zhang Ziquan's colleagues, Tang Haifeng, said the late officer said he always wanted to be like his father and never regretted the career path he had taken, although working in narcotics was dangerous. After graduating from Yunnan Police College in 2007, Zhang Ziquan became a police officer and joined the anti-drug unit in September 2010.

He helped solve 158 major drug trafficking cases, with more than 20 metric tons of illegal drugs seized. He was also involved in the successful investigations of 46 narcotics cases, according to the bureau.

In an interview before his death, Zhang Ziquan said:"I didn't choose this path deliberately. I just felt that I had to be a police officer, and I think I am a qualified police officer."

In November, police seized a suspicious foreign woman at the border. She later tested positive for COVID-19 although she had no symptoms.

Police learned that she had been with the head of a cross-border criminal gang for four days in Mengding town, Lincang. The pair had traveled to multiple townships raising fears the virus may have been spread to residents.

A state of emergency was declared in Mengding due to COVID-19 cases. The township was closed to outsiders and all residents had to undergo nucleic acid testing.

The public security bureau formed a task force to investigate the case and stop the spread of the virus. Zhang Ziquan was one of its members.

After several days, the task force arrested the gang's ringleader. Zhang Ziquan and his colleagues interrogated the man 17 times and eventually gained key information on the gang's criminal activities.

They had been smuggling foreign women into China via Lincang for work and marriage. The undocumented women had no rights due to their illegal status.

The task force later traced the movements of three foreigners with COVID-19, along with 227 people with whom they had come into close contact. They also located another seven smuggled women. Tang said while they were making huge progress on the case the workload intensified and Zhang Ziquan started to experience health problems.

On Nov 22, Zhang Ziquan's face turned pale and he broke out in a sweat after finishing an interrogation, Tang said. "We advised him to have a rest to check his health, but he refused, saying he would rest after finishing the investigation," he said.

On Dec 1, Zhang Ziquan and his workmates went to Suzhou city, Anhui province, for further investigations and arrested six suspects, with local police's support. However, Zhang Ziquan had reached his physical and mental limits and fainted after returning to his hotel on Dec 3, Tang said.

Although he was rushed to the hospital, Zhang Ziquan died on Dec 15 from a cerebral edema.

When his wife Li Lianchao heard the news, she collapsed.

In February, with the support of her mother-in-law, Li started work."I used to be well-looked after by my husband, and he helped me to do almost everything. But now I must stand up by myself," she said.