"The expectation is that this program will help to save lives," De Icaza said. "The program is working."
Between 2,500 and 2,700 migrants attempting to cross America's southwestern border are captured daily, U.S. officials said; and since October, 263 have died trying. Many succumb to dehydration, heat exhaustion, drowning or motor vehicle accidents.
Immigrant rights groups in California say such tragedies underscore why U.S. and Mexican authorities should channel resources into combating the job shortage in Mexico, one of the prime reasons migrants cross the border.
"As long as there is poverty south of the border and the need for cheap labor in the United States, you're going to have this problem," said Emilio Amaya, executive director of the San Bernardino Community Service Center, a not-for-profit group that provides social and legal assistance to immigrants in Riverside County. "We need to find a more reasonable approach to the migration problem."
"The immigration law is dysfunctional," Sambrano said. "It's broken, and it needs to be fixed so that it is easier for people to immigrate here legally."
The activists also contend that few migrants who are caught go home willingly. Instead, they say, U.S. immigration officials and Mexican consular officers force them to return.
"Border patrol officers have become de facto immigration judges," Sambrano said.
U.S. border protection officials disagree. They say that those caught are typically returned as soon as possible through their point of entry, and that few would qualify for political asylum.
Chavez said many who have attempted to cross were now thankful for a program that delivered them home -- all expenses paid.
"These volunteers are tired of living at the border," the official said. "They want to return to their home. We see it as a once in a lifetime opportunity to prevent the loss of life."
But critics say many migrants view a trip home as a temporary setback.
"It's nothing more than a shell game," said Jennifer Allen, executive director of Border Action Network, a Tucson-based immigration advocacy group. "It's just shifting migrants from place to place."
And many are simply not willing to stay put. "Sometimes, the same day, they already start their trip back to the United States," Sambrano said.
