The Chinese graduate accused of being Mexico's 'fentanyl king'

Zhang's alleged involvement in the drugs trade came to an abrupt end when he was arrested in Mexico on 31 October 2024.

A judge took the controversial decision to place him under house arrest, but Zhang managed to slip out – reportedly through a hole in a wall – and flee by private jet to Cuba and then on to Russia.

Russian border officials detected his forged papers and he was sent back to Cuba, which returned him to Mexico, from where he was extradited to the United States.

His arrest made headlines around the world. The alumni network of Beijing's Peking University, where Zhang had studied Spanish, was stunned.

"Everybody was talking about it," says Alex. "It was such a shocking story and he's probably one of the most famous people Peking University produced."

In Culiacán, the cartel members say Zhang's absence was felt immediately.

Luis says it became "really hard to get the precursors".

"They took the man and that caused a mess," says Enrique. He says Zhang was "the one with the connections" in China, and the cartels had to "start from scratch and build a new route".

Around the same time, the United States' Drug Enforcement Administration began to detect a decline in fentanyl purity, which it said was "consistent with indicators that many Mexico-based fentanyl cooks are having difficulty obtaining some key precursor chemicals".

But disruption in drug supply chains is usually temporary, in what Dittmar describes as a "constant game of cat and mouse".

Her research has tracked how, when brokers are removed or key chemicals controlled, fentanyl producers adapt by finding substitutes and learning new processes.

Individuals in the supply chain can also be replaced – even, according to the cartel members, ones as deeply and widely connected as Zhang is alleged to have been.

Enrique says there is already someone in the frame – another Chinese person, but he says he can't say more "for my own safety".

Another cartel member, who describes himself as a coordinator responsible for moving goods and personnel within the cartel, says that although "all this started because of him [Brother Wang]… he left lots of connections to help us keep going".

"If he's gone, someone else will step in… the business will not stop."

Additional Reporting by Ruth Evans and Miguel Angel Vega