Rodrigo Cruz-Perez for The New York Times

C. Ramon Contreras Orozco is a local official in La Ruana.

LA RUANA, Mexico — Jittery families cram into his tiny office here, daily. Hundreds more have appeared at the San Diego border 1,500 miles away, clutching an official-looking letter bearing his name, gambling that its description of the violence in this blistering stretch of central Mexico will help them gain asylum in the United States.

The letter has quickly become a document of hope for the desperate. And the writer, an obscure local official named C. Ramon Contreras Orozco, keeps delivering, creating an unusual bureaucratic tangle that is testing American asylum policy.

"I'm trying to help," said Mr. Contreras, the jefe de tenencia, or occupancy chief, of this battle-scarred town, where a drug cartel has declared war on residents. "People keep coming, telling me: 'I'm afraid for me and my children. I need to go.' "

Asylum requests along the border with Mexico are soaring: claims more than doubled to 36,000 in fiscal 2013, from 13,800 in 2012. American officials believe that Mr. Contreras's letters were presented in nearly 2,000 of the most recent cases, turning him into a focal point for the anxiety over violence in Mexico and making his letter a case study for contentious issues on both sides of the border.

Indeed by furiously churning out documents that highlight Mexico's inability to protect civilians in this region of avocados, citrus and drugs, Mr. Contreras, 38 — a hefty lime farmer in his first government job — has managed both to shame his own country and to sign his way into the latest immigration feud in the United States.

"I'm just verifying reality," Mr. Contreras said, sweating at a too-small desk in an office without air-conditioning. "I'm not doing anything wrong."

Mexican officials have nonetheless become frustrated by attention to this agricultural area's slide into chaos, with drug cartels battling armed self-defense groups. And in Washington, influential lawmakers, including Robert Goodlatte, the Republican chairman of the House Judiciary Committee, are increasingly concerned that criminals are abusing the asylum process, cheating their way into the country and disappearing for at least a few years until their cases are heard.

Mr. Contreras's efforts rouse both concerns. In the 2013 fiscal year, most of the petitions for asylum based on a "credible fear of persecution or torture" came from Central America. But of the roughly 2,500 cases that came from Mexico, Mr. Contreras estimated that nearly 80 percent of them involved his letters. Officials with the Department of Homeland Security said they considered that more or less accurate.

And each case is a riddle. Are Mr. Contreras's assertions of the dangers here enough to give emigrating families a chance of asylum in the United States? Are the letters showing up at the San Diego border even originals?

Sometimes yes, sometimes no, immigration authorities say. The circumstances are often so murky that even members of the same family, carrying the same letter, say they have received different decisions on their requests to stay in the United States and apply for asylum.

"The letters are a product of need," said the Rev. Manuel Amezcoa, 49, a Roman Catholic priest who works in this part of Mexico. "But the results are complicated."

It all began in mid-March, Mr. Contreras said, when a young woman appeared in his office begging for a way to reach her grandfather in the United States. Just a few weeks earlier, on Feb. 24, residents had formed a self-defense group and publicly challenged the Knights Templar drug cartel, which led to a vicious gun battle near the town plaza just across from Mr. Contreras's office.

The Knights Templar then made it deadly to pick or pack limes, taking away this fertile valley's main livelihood. Gas had also become scarce because suppliers feared driving in, and the municipal president had just fled amid accusations of cartel ties, suddenly making Mr. Contreras, who used to spend much of his time certifying property transfers, all that was left of local government.