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Immigrants to the U.S. who were victims of a serious crime can apply for something called a U visa. It gives legal status to victims who help bring violent criminals to justice. The program was created 15 years ago, but it took another eight before it actually began. Each year, the cap on the number of visas issued is reached faster and faster. As Alexandra Starr of NPR's Codeswitch team reports, the program's proving controversial.

ALEXANDRA STARR, BYLINE: It's a Saturday afternoon in a basement apartment in the Bronx. Daisy Castillo is telling two of her daughters what's for lunch.

DAISY CASTILLO: Chicken, rice with mashed potato.

STARR: In her native Honduras, Castillo used to cook for a living. She worked as a street food vendor, but she didn't earn enough to support her children. So seven years ago, she left them in the care of her mother and crossed the border into the United States.

CASTILLO: (Through interpreter) I thought I would be coming for a year, a year-and-a-half. I said, I'll make enough money to build a house, and then I'll be back with my kids.

STARR: Castillo was pregnant with her fifth child, Kiara, when she arrived. In the U.S., she struggled to find work as an undocumented immigrant and new mother. She also entered a relationship that turned abusive. Three years ago, her former boyfriend beat her to the point where she was hospitalized. After that, Castillo declared she was going back to Honduras.

CASTILLO: (Through interpreter) I said, I don't want to be here anymore. I want to be with my children.

STARR: But then caseworkers at the shelter where Castillo had sought refuge counseled her about the U visa. If she cooperated with police to bring a case against her abuser, she could become a legal resident, and she could bring her sons and daughters over from Honduras.

CASTILLO: (Through interpreter) When they told me I could bring my kids, I said, OK, I'll stay.

STARR: 10,000 U visas are given out every year. A lot go to people like Castillo. Carmen Rey is an attorney at Sanctuary for Families, an organization that represents survivors of domestic violence. At one point, she was Castillo's lawyer. Rey says the U visa has helped her make the case to clients that they should pursue cases against their abusers.

CARMEN REY: The idea of the U visa was a way to get immigrant communities to not be afraid of law enforcement.

STARR: Local law enforcement officers play big role in the U visa process in part to ensure that immigrants do not fabricate crimes to qualify. Police officers have to attest that the victim has been helpful in their investigation. Chris Blue, the chief of the Chapel Hill Police Department in North Carolina, feels a little uneasy about that. He thinks the U visa may muddle a message he's been at pains to communicate - that his department is not the immigration police.

CHIEF CHRIS BLUE: I think that's an unintended consequence of a well-intentioned program, but I do think it can potentially send mixed signals about local law enforcement's role.

STARR: That said, Blue's department does certify U visas. Not all police departments do.

DEBORAH WEISSMAN: So you have what we've called geography roulette.

STARR: Deborah Weissman is a professor at the University of North Carolina law school. She says that in some jurisdictions, district attorneys and sheriffs say they don't believe in rewarding undocumented immigrants for reporting crimes.

WEISSMAN: There are some agencies across the country that have a policy of refusing to certify any U visas.

STARR: So in that sense, Daisy Castillo was fortunate. Law-enforcement cities with a long history of receiving immigrants, like New York, tend to be receptive to certifying U visas. Castillo is grateful she now has legal status, but it didn't solve all of her problems. At this point, she's been able to bring over just one of her children, 10-year-old Caroline. The three oldest remain back home.

CASTILLO: (Through interpreter) Seeing what I've suffered through here, far from my children, I wouldn't have left them. I would've tried to be with them.

STARR: But Castillo hopes her family will be reunited in the United States. That, she thinks, would make her initial journey here worth it. Alexandra Starr, NPR News, New York. Transcript provided by NPR, Copyright NPR.