The investigation, which used 800 law enforcement officers, the largest deployment in a human smuggling investigation, singled out what the authorities said were suspicious companies running shuttle vans provide a key link in the chain that carries illegal immigrants from the border to cities across the United States.
But the sweep was also the biggest example of whatimmigration agency officials said was a ramped up effort to curb illegal immigration by focusing more on breaking up the criminal organizations that transport people and the businesses that facilitate these networks than on simply making mass arrests of illegal immigrants and deporting them.
“What we are trying to do is rip this thing out by the roots,” John Morton, the director of the Immigration and Customs Enforcement agency, said in an interview here. “We are taking out the whole industry and giving such a shock to individuals that they won’t recover as they have in the past.”
While some 47 people were arrested Thursday, including some in Mexico in what officials called unprecedented cooperation with officers there, only about 17 were illegal immigrants being smuggled, and some of them will be granted permission to remain in the United States to serve as witnesses in the case, Mr. Morton said. A similar raid in Houston in February included the arrest of 80 illegal immigrants found when the businesses were raided.
Mr. Morton said the arrests would not end smuggling. That would be an ambitious goal: more people are ferried across the border here than in any other state. But Mr. Morton predicted the raid would disrupt a pipeline that has accounted for a “significant amount” of the illegal immigrants traveling deeper into the United States.
The announcement of the arrests, which focused on four shuttle van businesses in Tucson and one in Phoenix, comes at a time when the federal government has been under fire over its role and performance in immigration enforcement.
Two weeks ago, a rancher near the border was killed on his property, and the police suspect he encountered a smuggler. Since the killing, an outcry has risen over whether the federal government was doing enough to secure the border. This week, the Arizona Legislature moved closer to adopting what is widely believed to be the most stringent immigration enforcement bill among the states, giving local police agencies broad powers to check people’s legal status.
Immigrant advocacy groups on Thursday denounced what they called a climate of fear, deploring the ICE operation for coming at the same time as the legislation. A handful of protesters outside the United States attorney’s office here chanted, “We are going to beat back John Morton’s attack.”
In response to their concerns, Mr. Morton said the agency’s activity often generated “rumors and wild conjecture” but that no intimidation was intended.
Mr. Morton said the crackdown on the shuttle service industry had been stretched back more than a year and was not related to the legislation or the anger over the rancher’s killing.
But he reiterated the Obama administration’s promise to take up an overhaul of immigration law and said the arrests represented an effort to “step up our game” and attack smuggling organizations by going after the leaders.
“That is what this is all about, border security,” Mr. Morton said.
For nearly a decade, federal immigration authorities have been stymied by a fleet of shuttle vans, similar to those that carry people to airports and the like, that they say have operated under a veil of legitimacy.
When stopped, even if the passengers were found to be illegal immigrants, drivers would profess not to know the legal status of their passengers, and prosecutors doubted a case would stick.
“That has been a very hard defense to overcome,” said Matthew Allen, who directs ICE in Arizona. “Now we have been able to get past that and show they do know.”
Smugglers would guide people, typically on foot, across the border. A car or sport utility vehicle would pick them up and take them to Tucson, where in “very quick handoffs,” an ICE official said, the migrants would board the shuttle vans to Phoenix. From there, after having paid fees of several thousand dollars — $75,000 in the case of some Chinese immigrants — to be taken into the United States, they would transfer to private cars and head to destinations across the United States.
Mr. Allen said that agents had made extensive use of surveillance, technology and leads from people in the United States and Mexico to build the case, which began about a year ago.
He said agents had recovered extensive records, including fake tickets the passengers would show law enforcement officers in case the van was stopped for an immigration check. In those situations, it has been difficult to prosecute the drivers because it was nearly impossible to prove they were aware their passengers were in the country illegally.
Agents on Thursday morning searched the offices of Sergio’s Shuttle on a busy street lined with mechanic shops, bodegas and small businesses. Two vans, with a tiger emblem on the side, sat in front of an office that advertised a schedule to several cities on both sides of the border.
No one answered the phone number listed on the side of the van or the office.
Alfonso Quintero, who owns a muffler repair shop a few doors down, said he often saw people coming and going from the vans at all hours but nothing raised his suspicions.
“I didn’t see anything illegal,” Mr. Quintero said. “Looked like they just wanted a ride."