Federal immigration and local law enforcement officers arrested 22 people in the Pittsburgh region who are in this country illegally as part of a five-day sweep across the state and in Delaware called "Operation Return to Sender."

The operation resulted in the arrests of 115 people, including fugitives and other immigration violators. In this area, people were arrested in Robinson, Glassport and Aliquippa.

In Aliquippa, officers went to a home on Spring Street about 6 a.m. Monday, looking for a fugitive who had an outstanding warrant. That man wasn't there, said Aliquippa Officer John Gable, but there were five other illegal Mexican immigrants in the house who were arrested.

In addition, agents found four loaded guns in the house, said Marc Raimondi, a spokesman with U.S. Immigration and Customs Enforcement.

Since Operation Return to Sender began in late May, there have been more than 12,000 arrests nationally. Although federal agents specifically target fugitives, any other immigration violators found can be arrested as well.

"This isn't a random sweep," Mr. Raimondi said. "We're targeting people who have already had their day in court." They are immigration violators who have been arrested at least once before -- often in traffic stops -- and whose deportation has been ordered by immigration courts.

Vic Walczak, legal director for the ACLU of Pennsylvania, said he doesn't have a problem with federal agents picking up those who have been found guilty. But he questioned the process used in getting illegal immigrants to court in the first place. "We're concerned the police may be stopping and questioning people without having probable cause," he said. "Simply being Latino is not probable cause; there has to be a legitimate basis for a stop." Otherwise, it's "ethnic profiling," Mr. Walczak said.

The 115 arrested this week are from 29 different countries. ICE officials were not able to say how many were fugitives, but did say, that just 16 had criminal records. "There are far more non-criminal fugitive aliens than criminal," Mr. Raimondi said.

In fiscal year 2006, which concludes at the end of the month, ICE fugitive teams have arrested more than 23,000 people. There are now 52 such teams, up from 18 last year.

In all, 65 law enforcement officers worked on the most recent operation, including ICE agents and local police officers.

"Although the operation lasted just five days, the planning for it spanned 65 days," Mr. Raimondi said.

In this fiscal year, the U.S. attorney's office has prosecuted 60 defendants on immigration violations, up from 35 last year and 22 in 2004.

The vast majority have involved illegal Mexican immigrants, said U.S. Attorney Mary Beth Buchanan. "In the aftermath of the events of September 2001, we have had a greater focus on cases involving our borders," she said.