(CNN) -- The women's lives have taken different paths since the days they were born.
Brenda Vazquez is a 29-year-old elementary school teacher in Matamoros, Mexico. Laura Castro lives across the border in Brownsville, Texas. She is a 32-year-old housewife who helps her husband manage several stores.
They share one thing in common: Both say they were delivered by midwives in south Texas, but pressured by U.S. Border Patrol agents to deny their U.S. citizenship.
Their problems began, according to attorney Jaime Diez, when a group of midwives along the U.S.-Mexico border were found guilty of selling birth certificates to people who were not born in the United States.
"Now all the midwives in the area are suspected of committing fraud," said Diez, who said his office regularly sees cases of people delivered by midwives in Texas. Some of them are struggling to get passports because officials question the validity of their birth certificates, he said. Others have been deported and had their identification documents confiscated at the border, he said.
Vazquez, who Diez is representing in a federal lawsuit filed last week, said she was intimidated into signing a document swearing she was not a U.S. citizen at a border crossing in Brownsville, Texas, last year.
"He said, 'You'd better cooperate with me, because if you don't, you're going to jail. I had to lie and say that I was not a citizen. ... I was quite scared. I was crying," the second-grade teacher said.
A U.S. Customs and Border Protection spokesman said he could not comment about Vazquez's case or other such cases "due to pending legal action."
Border patrol agents are "obligated to ensure that documentation presented to establish citizenship is proper and correct and was issued to the person presenting the documents," spokesman Bill Brooks said in a statement.
A 2012 report from the Texas Office of the Inspector General said a fraud investigation had been "substantiated" and Vazquez's birth record had been flagged, noting Vazquez's signed confession and the fact that officials found birth certificates for Vazquez in both the United States and Mexico. The report said the case would not be prosecuted because it was beyond the statute of limitations.
Vazquez said her parents obtained the Mexican birth certificate so she could study in Mexico.
Vazquez said she has never lived in the United States, but wants to fight to regain her citizenship.
"With crime as it is in Mexico, something might happen, and as a citizen I would go live there," she said.
Laura Castro said she faced a similar situation with her mother and sister at the same border crossing in 2009.
"My sister got desperate and signed the paper," Castro said.
A border patrol agent told her that her mother had admitted to buying false identification documents for the family.
"He kept asking me the same thing, and I replied the same thing, that I was a citizen. ... I said I was not going to sign because I did nothing wrong, and they let me go. ... They sent me back to Mexico," she said.
Nearly a year later, authorities returned Castro her U.S. passport after she filed a lawsuit, she said.
But Castro said she remains frustrated.
"We were very humiliated. We were treated like criminals," she said.
The issue has come up before. In 2008, the ACLU sued the federal government on behalf of nine people, arguing that authorities were unfairly discriminating against passport applicants.
"For countless Latinos who were delivered by midwives in the Southwest ... trying to obtain a passport has become an exercise in futility," the ACLU said in a statement at the time. "Although midwifery has been a common practice for more than a century, particularly in rural and other traditionally underserved communities, the U.S. government has imposed unsurpassable hurdles on midwife-delivered Latinos to prove their citizenship and eligibility for U.S. passports -- even when their citizenship has already been established in the past."
In a 2009 settlement, the State Department agreed to a new set of procedures for such passport applications.
But the settlement said the department denied the ACLU's accusations, and noted that "there has been significant fraud by midwives and other birth attendants certifying births as occurring in the United States when they have not occurred in the United States."
Diez said U.S. authorities need to do more to address the problem.
"If they doubt that a person was born here and they can't criminally charge them, then give them a process in which they can send their documents to be investigated, give them a chance to be before a judge with a lawyer, and in which there could be a process in which they make things right. That's how it should be when we are talking about the citizenship of someone," he said.