W hen cousins Aldo Mayorga and Bernabe Castro went to a Castroville nightclub to enjoy a few beers in late July, they thought the only risk they might face was their wives’ disapproval.

But a late-night fight between two other bar patrons summoned several sheriff’s deputies, who told the crowd to clear the bar. Mayorga clashed with one of the deputies when he tried to return to use the bathroom. In the chaos, the deputies took him to the county jail.

“I didn’t commit any crime,” Mayorga recounts by phone in Spanglish. “I thought I’d leave [jail] because there was no reason for me to be there.”

But within days of being booked on misdemeanor charges of obstructing an officer and public drunkenness, the 32-year-old father—whose wife and three children are U.S. citizens—was deported to his native Mexico. Mayorga had lived in Castroville for more than a decade and worked in construction without papers.

He is one of the more than 275 people from Monterey County to be deported under a new immigration enforcement program called Secure Communities, which began April 6. The program sends the fingerprints of everyone booked at the jail to be checked against an Immigration and Customs Enforcement database to see whether they’re in the country illegally. When there are matches, ICE instructs the jail staff to put “holds” on those inmates so they will face deportation rather than release.

“One of ICE’s priorities is to ensure that potentially dangerous criminal aliens aren’t being released back onto the streets of our communities,” says ICE spokeswoman Virginia Kice.

Before the fingerprint program, ICE agents would review jail records, but immigrants who had been let out on bail would often go undetected.

When Homeland Security Secretary Janet Napolitano announced last week that the U.S. had deported a record-breaking 392,000 immigrants this fiscal year, she credited Secure Communities with boosting those numbers. Congress directs ICE to expand the program nationwide by 2013, but it hasn’t been welcome everywhere.

Both San Francisco and Santa Clara counties want to opt out, citing concerns that it could cause immigrants to fear police.

Eileen Hirst, spokeswoman for the San Francisco sheriff’s office, says with Secure Communities in place, an undocumented victim could get on ICE’s radar by calling 9-1-1. “It is not unusual for law enforcement to arrive at a domestic violence call and not be able to sort out who is the victim and who is the batterer, and both people are taken into custody,” she says.

Monterey County supervisors, on the other hand, say they haven’t heard any complaints from constituents. Sheriff Mike Kanalakis supports the program, as does his challenger in the Nov. 2 election, Scott Miller.

Kice says the program has identified serious Monterey County criminals for deportation, including an individual who was arrested on drug charges and has been convicted of multiple felonies, as well as a convicted child molester. Both will be sent back to Mexico once their criminal sentences are completed.

Commander Mike Richards, a spokesman for the Sheriff’s Office, says Secure Communities has been “very effective.”

He says the immigrant community should still feel comfortable collaborating with police: “We are not targeting people who are here illegally. We are targeting people who are committing crimes who happen to be here illegally.”

But it is not only hardened criminals who are impacted by the program. ICE records show that Secure Communities is deporting immigrants accused of minor offenses as well as those who have only violated immigration laws—such as overstaying a visa, ignoring a deportation order or returning to the U.S. after being deported.

As of Sept. 30, almost half of the Monterey County arrestees with ICE holds had no criminal record besides immigration offenses, according to ICE data. Twenty-two percent had committed what ICE considers the most serious crimes.

Local immigration attorney Barbara Soukup says one of her clients was taken into custody after driving repeatedly without a license. His fingerprints revealed that his visa had expired, and he wound up in deportation proceedings.

As for Aldo Mayorga, the father swept up in the bar fight, his fingerprints showed he was caught by border patrol while attempting to cross back into California after a 2001 visit to Mexico.

That history allowed ICE to deport him immediately. Now his American family is trying to start over in Zacatecas, Mexico.

Back in Castroville, his cousin still hasn’t gotten used to Mayorga’s absence. “His life changed 360 degrees,” Castro says. “It makes you feel powerless.”