TENENEXPAN, Mexico - The route that Noemi and Andrea Quezada traveled from this small farming village into the United States is an inhospitable passage, but one that many of their family members have chanced over the years in an effort to escape grinding poverty.

The women, Noemi and her niece Andrea, did not have papers to enter the United States legally, so they stole across the harsh desert from Nogales, Mexico, to Arizona.

They either walked for four nights with their children in their arms or crammed into the back of a pickup truck for two days with dozens of others pressed up against them, according to family members here.

"Many, many of us are over there," said Beatriz Quezada Rincon, their cousin and a village hairdresser. "There is no money to sustain us here, so we have to go there to look for jobs. The crossing is very hard, but it is worth it."

Last week, Noemi and Andrea Quezada's children - 9-year-old Ricardo Solis Quezada Jr., 10-year-old Alexis Espejo Quezada and 9-year-old Lucero Solis Quezada - were found dead in their Northwest Baltimore home, one decapitated and two nearly beheaded.

Family members in Mexico say that the women, like so many before them, took their children to the United States to improve their lives and give them better educational opportunities.

It is impossible to know how many people like the Quezadas slip through the border or how many of those caught tried to cross again and succeeded.

But the flood of Mexicans trying to enter the country illegally continues. Last year, border patrol agents intercepted almost a million people crossing, according to Mario Villarreal, spokesman for U.S. Customs and Border Protection.

The Sonoran desert extends well into Mexico, so many people attempting to make the journey are physically spent well before they reach the U.S. line.

Human smugglers, called coyotes, will tell their "clients" that the walk across the border takes eight to 12 hours, Villareal said, but in fact it lasts three to five days.

"It's rugged terrain, cactus, sand, brutal sun; the temperature's incredible, no shade," he said. "Unfortunately, people often succumb to the climate."

The men arrested in the killings of the Quezada children - Policarpio Espinoza, 22, and Adan Espinoza Canela, 17 - also crossed into the country by walking through the desert, according to authorities.

Attempts intercepted

Sometime during summer 2000, Espinoza made his first attempt to leave Mexico through the Arizona desert. Border patrol agents intercepted him and the others he was traveling with and handed them over to Mexican officials.

It was the type of handover that federal agents make regularly along the Southwest border, one they know won't stop determined crossers for long.

Sure enough, border patrol agents intercepted and returned Espinoza at least two other times that summer, according to federal officials. But eventually, Espinoza got across.

Two years later, federal officials say, Adan Espinoza Canela followed. He told federal agents this week that he, too, walked across the Arizona desert. He was never intercepted.

It is unclear how the two got from Arizona to the house in Baltimore County where they lived until their arrest last week.

Since Sept. 11, 2001, the federal government has increased its patrols along the country's border with Mexico. There are more border patrol agents than ever before - about 11,000 - and a single agency, U.S. Customs and Border Protection, working solely to monitor the nation's edges.

Crackdown in Arizona

In March, federal officials announced an Arizona Border Control Initiative, which would officially increase efforts to crack down on immigrants illegally crossing the border between Mexico and Arizona - a section that officials say has been particularly problematic.

"There are people who cross legally and illegally every day," said Dean Boyd, a spokesman for U.S. Immigrations and Customs Enforcement.

In a report earlier this year, the Urban Institute estimated the undocumented immigrant population at 9.3 million as of 2002 - with estimates that between 120,000 and 150,000 of those immigrants are in Maryland. A prior estimate from the Department of Homeland Security put the percentage of such immigrants coming from Mexico at 70 percent.

"The driving force behind the migration phenomenon is economic - people wanting to enter the U.S. because of economic need," Villarreal said.

In Tenenexpan, where working as a farmer pays $50 a week, the Quezada family couldn't agree more.

The adventurous spirits who want to try their luck getting across the border pay a coyote about $1,400. Entry into the United States is never guaranteed, said several family members who have successfully made the trip and later came back home.

"I was very scared of the crossing," said Rafael Quezada Huerta, 38, who came into the country illegally in 2000 and lived in Los Angeles exactly one year and 16 days. "You hear about a lot of accidents in the desert."

Huerta sold his family's only truck to pay the coyote. His cousin who lives next door, Luz Maria Quezada, 37, borrowed money from friends, family and neighbors in 1999 to pay her coyote. His brother, Pasqual Quezada, 55, sold three cows in order to make his trip last year. All have since returned.

For Luz Maria Quezada, a single mother of three, the trip was long, hot and terrifying. She went to earn enough money to finish her house so her children would have a nice place to live.

Her crossing was a four-day trek in which she and two others walked during the night and slept on the ground during the day. They carried water and chicken to sustain themselves.

"I had no idea if I would make it alive," she said.

She ended up in Phoenix, where she worked in a restaurant for three years.

Huerta ended up in Los Angeles cleaning a wood furniture factory for $5 an hour. But he sighs heavily when he explains how he got there.

He piled into the back of a covered pickup truck with two dozen other men - each sitting in a line with open legs, almost in each other's laps.

During the two-day trip, the coyote would occasionally pass back some water. There was no food; no one spoke a word during the sweltering ride.

Huerta then went to see a man the coyote recommended and was given a phony green card for $60. That allowed him to get a job with health benefits at the furniture factory.

He liked the life because he worked from 6 a.m. until 3 p.m. In Tenenexpan, he works in the fields tending cattle and horses from 6 a.m. until 8 p.m.

"If you work here you can't save any money," Huerta said. "Over there, if you work hard for a year, you can buy a car. Getting over there isn't pretty, but everyone knows that."