One reason for that, officials said: the convergence of drugs and illegal immigrants in the Sonora-Arizona area. The dominant drug mafia in the region, the Sinaloa cartel, "saw an opportunity to get into Chinese smuggling," said Border Patrol spokesman Mario Escalante.
The evolving alliance between traffickers of drugs and of immigrants -- once separate specialties -- is complex. According to investigators, drug lords use their firepower to control turf and tax others for the use of border corridors, known in Spanish as plazas, charging $50,000 to $100,000 a week.
"The drug trafficking organizations in the plazas control who smuggles, what they smuggle, where they smuggle," Allen said.
At times, when drug mafias are at war or when moving drug loads is difficult, muscling in on the human smuggling racket brings easy profit and less risk, Pacheco said.
And whereas violent retaliation is common among drug traffickers after a big bust, it's less so among smugglers whose immigrants are caught.
"Losing Chinese, you lose money but not an investment upfront," Pacheco said. "They don't buy the Chinese, they charge them."
Nonetheless, Allen said, "the drug and alien smuggling groups are still separate entities. Once human smugglers make it into the U.S. with their loads, there is not coordination."
Chinese immigrants intercepted by the Border Patrol have often spent months on the road.
"Some speak a few words of Spanish," Delap said. "Most of them communicate with hand gestures and body language."
Delap, who majored in political science and minored in Chinese at Brigham Young University, taught English in Yunnan and Xinjiang provinces eight years ago. He has been with the Border Patrol two years.
He sees the chance to use his knowledge of Chinese language and culture as one humanitarian aspect of the Border Patrol, which frequently rescues immigrants from the desert.
Although his conversations with Chinese immigrants focus on basic information, it is clear that his presence is reassuring.
"A lot of times at the end of the shift when I have to go, they realize that and a lot of questions come flooding out: Where are they going, when will they be leaving the detention facility, what will happen," he said. "I explain the best I can."