Ren Shasha, 32, knows what it takes to bust a heroin deal — an apron, some sunflower seeds, and the natural advantage that undercover female police have of going unnoticed by criminals.

Established in 2015, Ren's team is the first all-female anti-drug unit in China's national border defense system.

"I joined the team at its founding when there were only three female officers. Now it has expanded to eight," said Ren of the female investigation unit of the Dehong Border Administration Detachment in Yunnan province.

Many drug traffickers possess strong counter-surveillance skills, but female officers have natural advantages in certain tasks. Police skills such as disguise, surveillance and tracking often result in positive outcomes when women are involved, Ren said.

In a recent case, the team received intelligence about a potential drug deal taking place in a parking lot in Mangshi city, Dehong Dai and Jingpo autonomous prefecture. With its proximity to the notorious Golden Triangle, Southwest China's Yunnan province remains the front line in the country's efforts to stem the cross-border flow of illicit drugs.

"I disguised myself as a restaurant worker and positioned myself directly facing the main entrance of the parking lot. I remember wearing a restaurant apron and buying some sunflower seeds. Then, I sat around chatting with others to make the drug dealers believe I was genuinely working there," she said.

Hours later, a white car entered the parking lot and circled a few times. After confirming that it was safe, the passengers got out and pretended to move a tire into the car.

"When they were about 2 meters from the vehicle, we arrested them. We seized more than 30 kilograms of heroin in this case. Under the car mat we also found a handgun and a dozen bullets," Ren said.

Making an arrest is only the beginning of the process.

"Applying for arrest warrants can take about a month, followed by around two more months to gather evidence for the prosecutors," she said.

"A case takes at least six months before it enters a lengthy trial process. That's why we emphasize catching suspects in the act."