The Border Patrol is seeking to add 5,000 agents to its ranks.

A.E. Araiza / Arizona Daily Star 2016

Border Patrol agents caught Clemente Armenta crossing the border illegally near Nogales in 2013, two years after he was deported.

Arrests like Armenta’s for repeated illegal border crossings were once common in the Border Patrol’s Tucson Sector, but they have grown increasingly rare, agency statistics obtained by the Arizona Daily Star through a public-records request show.

Agents in the Tucson Sector made 277,500 arrests in fiscal 2000 that involved people who were arrested previously for crossing the border illegally. In fiscal year 2015, agents made 9,300 such arrests.

With that decline, the portion of Tucson Sector arrests for illegal crossings involving repeat offenders dropped from 45 percent to 15 percent.

Before his 2011 deportation, Armenta, who had five years of education, worked in Phoenix for 11 years to support his three children living in Puerto Peñasco, Sonora, court documents show.

The 34-year-old Mexican national pleaded guilty to a felony charge of illegal re-entry after deportation. He was sentenced in April 2014 to 57 months in federal prison and three years of probation.

Prison terms are a key part of the Border Patrol’s “consequence delivery system,” which is meant to deter people from repeatedly crossing the border illegally.

The Border Patrol attributes the decline in recidivism — which refers to repeated illegal border crossings — to the consequence delivery system, additional agents and detection technology, better infrastructure and partnerships with other law enforcement agencies, Tucson Sector spokesman Agent Vicente Paco said.

All of those factors help make Southern Arizona an “undesirable place for smuggling,” Paco said.

Annual apprehensions in the Tucson Sector fell from 616,300 to 63,400 between fiscal 2000 and 2015, agency records show. Border-wide, total apprehensions dropped from 1.64 million to 331,000 during that period.

In fiscal 2016, total apprehensions grew to 409,000 along the U.S.-Mexico border.

The recently released statistics on repeat offenders are based on the Border Patrol’s fingerprint identification number system, which the agency uses to track people caught crossing the border illegally.

However, the agency regularly issues reports to the public that are based on apprehensions, which is a measure of the number of arrests, rather than actual individuals arrested. Which means, for example, one person — caught illegally crossing numerous times — can account for multiple apprehensions in the records.

As a result, determining how many individuals were caught crossing the border illegally over the years was problematic, given that it was widely believed many more repeat arrests occurred in the early 2000s prior to the expansion of border-security measures in the last decade.

The recently released statistics show Tucson Sector agents made 5.2 million apprehensions between 1999 and 2015. About 1.8 million of those arrests involved people who had been arrested previously, indicating agents arrested 3.4 million individuals during that period.

The statistical drop in repeat offenders has “a lot more nuance to it” than increased border security measures and enforcement of immigration laws, said Maryada Vallet, a volunteer and spokeswoman with the Tucson-based humanitarian group No More Deaths.

In recent years, more Central Americans crossed the border illegally as they fled violence and poverty in their countries, Vallet said. Many of them were trying to cross the border for the first time.

Border Patrol records show 46,900 apprehensions of children from El Salvador, Guatemala, and Honduras in fiscal 2016.

Volunteers with No More Deaths fear programs like Operation Streamline — in which defendants charged with crossing the border illegally face a judge in groups and are sentenced to prison terms — could raise the risk of migrant deaths, Vallet said, giving the example of migrants being reluctant to trigger rescue beacons in the desert if they fear ending up in prison.

Since 2001, nearly 2,500 bodies have been found in the Tucson Sector.

And the sector’s rate of 21 deaths per 10,000 apprehensions for fiscal 2015 was twice the rate of fiscal 2010.

But the risk of death or time in prison won’t deter many people who have strong ties to the United States, Vallet said.

“Their babies are here, their families are here,” she said. “Often times they’re more willing to take the risk to get back.”

An April 2016 Congressional Research Service report described enhanced border enforcement as a double-edged sword.

More enforcement likely contributes to deterring unauthorized entries, which reduces border-area violence and migrant deaths, protects border ecosystems and improves quality of life in border communities, the report stated.

But for border crossers who are undeterred, increased enforcement also may “encourage unauthorized migrants to find new ways to enter and to remain in the United States for longer periods of time, damage border ecosystems, harm border-area businesses and the quality of life in border communities, and strain U.S. relations with Mexico and Canada,” the report stated.

Contact Curt Prendergast at cprendergast@tucson.com or 573-4224. On Twitter @CurtTucsonStar.