"They don't have to answer, but nine out of 10 times they will freely admit to being illegally in the country," said the ICE official, speaking with National Journal on the condition of anonymity.
Then agents run their fingerprints to see if they have criminal convictions or an active deportation order. Most people don't fall into those priority groups, so they're usually released on the spot, even if they're undocumented, the official said. The New Orleans field office does not regularly track how many people their fugitive teams fingerprint with the mobile scanners.
Many of these operations have happened outside a popular chain of Hispanic supermarkets, according store managers and their customers. Lorna Torres, business controller for Ideal Discount Market, says stings take place about once a month outside one of their three stores in the New Orleans area.
"It definitely scares our customers away," said Torres. The chain's owner has gotten lawyers involved, she said, but they have no control over immigration enforcement that's not directly on their property.
Marta Escalantes avoids shopping at one of the chain's stores in her Mid-City neighborhood ever since her husband was picked up in the parking lot. The 33-year-old hotel worker was two months' pregnant that evening when she asked her husband, Ernesto Lopez, to buy her a watermelon to ease her nausea.
She remembers the sickening feeling when a friend called to tell her that immigration agents had raided the supermarket in Mid-City and that Lopez's car was still in the parking lot.
"I felt desperate because I thought I was going to be all alone with my little girl," said Escalantes, who cleaned streets in New Orleans after Katrina and now cleans hotel rooms.
Sure enough, her husband had been among those fingerprinted and detained. Lopez says he never told the agents where he was born, but they fingerprinted him anyway.
He says he was sitting in his car in the parking lot when an agent approached and repeatedly asked him where he was from. Lopez responded each time by saying that he lived in New Orleans.
The agent then told him to get out of the car, he said, and pulled Lopez's wallet out of his pocket without permission. The agent found identification from Honduras, so he handcuffed and fingerprinted Lopez with seven other customers agents had stopped. Those without past deportations were released, but Ernesto had been deported before.
An immigration judge delayed Lopez's deportation for one year so he could be with his wife when their daughter was born. The year ended in August, and he has a hearing scheduled in December to request another delay. That is the only option he has.
Lopez said he feels betrayed by the city he helped rebuild and feels targeted because of his skin color.
"After [Katrina] happened, we were all welcomed to come rebuild the city. And now they repay us with deportation and separating our families," he said.