This story was produced in conjunction with The Marshall Project.

CHARLOTTE — One morning last January, Maria made a call that would change her life.

Maria, a 39-year-old mother from Colombia, spoke no English. She had no friends nearby, no money and had overstayed her visa after coming to the U.S. legally. But after her fiancé allegedly assaulted her and her 15-year-old son during an argument, she said a prayer and picked up the phone.

"It was terrifying to call the police," said Maria, whose last name is being withheld because she is a victim of domestic violence. "But I dug up the courage. I told myself I had to do something."

That call would prove fateful. Maria's fiancé, a U.S. citizen named Danny, was charged with assault. In July, as Maria and her son appeared at the Mecklenburg County courthouse for a hearing related to the incident, federal immigration agents arrested them. Maria and her son were handcuffed and led away as she cried for her other child, a toddler she had left in daycare.

Their arrest is more fuel for a long-simmering debate over Immigration and Customs Enforcement's presence inside the courthouses of major U.S. cities, and raised questions about the agency's treatment of domestic violence victims.

"ICE coming in and arresting Maria and her son puts a lot of fear in a lot of people's heart," said Herman Little, the defense attorney who was with Maria that day. "You have a situation where undocumented victims are scared to come to court because they fear they are going to get deported."

In an exclusive interview with NBC News, the newly promoted deputy director of ICE, Matthew Albence, said that arrests of undocumented immigrants like Maria will continue, whether inside or outside a courthouse.

"If an individual is here illegally in this country, they're always subject to arrest for that criminal violation," Albence said. "We have compassion to all victims of crimes that are here illegally. We have compassion toward victims of crimes that are United States citizens that have crimes committed against them by illegal aliens. That said, we have a job to do."

Officials in several cities, including police chiefs and district attorneys, say that immigration enforcement operations inside courthouses have hampered their ability to investigate and prosecute crimes.

"We rely very heavily at the local level on cooperation from our witnesses and from our victims to ensure that cases can be prosecuted," said Denver City Attorney Kristin Bronson. "What we've found in Denver is people are not showing up because they're afraid that they might get apprehended in the hallways."

For undocumented victims of domestic violence, Bronson said, that fear is particularly palpable. Since President Trump's inauguration, she said, she's had to drop 30 cases of domestic violence because the victims were too afraid of deportation to cooperate and appear in court.

"It means that abusers are going without consequences," Bronson said. "It means that abusers are beginning to feel that they are immune from prosecution, and it's become, unfortunately, a tool to further victimize women who are the victims of domestic violence."

Matthew Albence NBC News

Under the agency's "Sensitive Locations" policy, ICE agents can only make arrests at schools, hospitals or places of worship under "exigent circumstances" or with prior approval. Courthouses are not considered sensitive locations. But some judges, including several state chief justices, attorneys general and other officials from cities around the country have asked ICE to include courthouses in the policy.

Houston Police Chief Art Acevedo told NBC News he worries about the collateral damage that federal immigration enforcement has on the communities he serves. "The courthouse should be a sanctuary for victims and witnesses," Chief Acevedo said. "If you lose witnesses, everyone else's crime goes up."

In New York, three district attorneys have asked ICE to stop making courthouse arrests, saying they had a 'chilling effect' on witnesses. Massachusetts Attorney General Maura Healy said in a statement that, overall, tougher immigration enforcement tactics are "undercutting our ability, as law enforcement, to develop the critical trust to keep our communities safe."

Albence disputed the idea that his agency's enforcement tactics are interfering with local justice.

"This whole notion that, you know, us arresting people at the courthouse is going to interfere with victims or witnesses — it's not," Albence said. "We are there targeting individuals who we know are here in the country illegally, have been charged or committed or convicted of a criminal violation, and we are taking enforcement action against those individuals."

Maria, 39, an undocumented immigrant from Colombia, was arrested by ICE last July after filing charges against her alleged abuser. "When someone is living some kind of abuse, no matter what kind, people need to speak up and seek help," Maria said. Hannah Rappleye / NBC News

"ICE has been making arrests in courthouses for many, many years, just like every other federal, state and local law enforcement agency does," Albence said. "If there are those that want to sensationalize that and put it up in the media and make a big story about it that we have changed our processes, maybe that's what's causing the concern."

ICE has arrested undocumented immigrants in courthouses for violations ranging from overstaying visas to misdemeanor cases to more serious crimes. Albence said that ICE works closely with prosecutors' offices and that courthouse arrests are just a fraction of the overall arrests the agency makes every year. Officers from other agencies, such as the U.S. Marshals, also have a presence inside courthouses. And, he said, the agency has been forced to use the tactic more frequently in cities that have refused to cooperate with federal immigration operations.

"It's a disingenuous position for any politician or local leader to come out and say, 'ICE should be going after criminal aliens and focusing their resources on criminal aliens,' while at the same time not allowing us into that jail or not turning that individual over to us when they're in their custody," Albence said. "It's intellectually dishonest."

'They made me feel safe'

Maria met her former fiancé Danny in Colombia. In 2016 she and her teen son entered the country legally, on a 90-day K-1 visa — often called a "fiancé visa."

She gave birth to the couple's son shortly after she settled in Charlotte, and looked forward to the future. But the relationship devolved, she said, as his behavior grew more controlling. The couple postponed their wedding. After her visa expired, Maria alleges Danny began to use her legal status against her.

"He told me if I tried doing anything, he would take my child [and] have us deported," Maria said.

While it is difficult for anyone in an abusive relationship to find the strength and resources to leave, it may be doubly so for a victim without legal status. Maria felt trapped. Her infant son was a U.S. citizen, and obtaining a passport for him would require the permission of both parents. She couldn't imagine leaving her child behind.

"In every case that I have where the abuser is documented and the victim is undocumented, immigration status is always used as a method of control," said Lisa Diefenderfer, Maria's immigration attorney and staff attorney with the Charlotte Center for Legal Advocacy. "Whether it's a threat, whether it's a promise, it is used as a means of control to keep a victim in fear, to keep them from reporting, to keep them from leaving, to keep them from seeking justice."

According to court documents and police reports, on the morning of Jan. 10 Danny became angry after Maria's teen son overslept his alarm and asked for a ride to school. Maria alleged that Danny twisted her arm behind her back as she held their baby, then only 13 months old. Maria, frightened, called out for her teen son.

Maria alleges that after her son confronted Danny, Danny kicked him in the stomach, punched him in the face and threw a ceramic sugar container at him.

Maria called the Charlotte-Mecklenburg police. An officer took her and her children to the hospital. "They made me feel safe," she said.

Danny was charged with simple assault for attacking the boy, a misdemeanor. Maria and her sons moved into a shelter for domestic violence victims. Maria filed an application for a protective order, which a judge later granted.

"This is not the first time Danny is abusive," Maria wrote in her application. "He insults me and my son all the time and has threatened to take [my infant] son away…He breaks and throws things when he is in a rage. He is controlling and demands to know what I am doing all the time. I can't continue to live like this. I want him to stay away from us."

Danny has not been convicted of a crime. NBC News reached Danny's attorney by phone, but she declined to comment. In court documents, Danny alleged that Maria used their infant son as a "shield," and that she and her teen son attacked him. He also alleged that Maria had assaulted him several times in the past.

Just over a week after the alleged incident, after Maria had requested a protective order, Danny filed charges of misdemeanor larceny and assault against her. He alleged that she abused him and stole items from their home, including a baby crib, a saucepan, and cell phones.

"These charges were bogus," Diefenderfer said. "After she filed for a protective order and filed criminal charges against her abuser, her abuser retaliated and filed criminal charges against her. It's a lot easier to make a case go away if your witness isn't there."

On July 9, Maria placed her toddler in the care of the courthouse daycare, and walked alongside her teen son into a courtroom. Though both charges against her were later dismissed — a prosecutor called Danny's claims "retaliatory" in court documents — Maria was reporting to court that day as both a criminal defendant and as a victim. She was a defendant in one case and a witness in the assault case against her alleged abuser for allegedly hitting her son.

After court, Little, Maria's defense attorney, was headed toward the elevator when he saw an agent in plainclothes slipping handcuffs around the wrists of Maria's teen son. He ran toward the boy, and then saw Maria.

"I try to approach the immigration agent and he tells me, 'Back up. Back up,'" Little recalled. "And I say, 'What do you mean? This is my client. I'm her attorney….What are you arresting her for?'"

Maria, afraid to be separated from her youngest child who remained in the court's daycare, was "hysterical," Little said.

The agent said, '"I don't have to tell you,'" Little said. "And I said, 'Not only is she a defendant, but she is also a victim. Her son is a victim'….All you can do at that point is just try to think of something, somehow, to make the situation better. [I told Maria], 'Don't worry. Everything is going to be all right.'"

After being processed at a local ICE facility, Maria and her son were released. Today, they both face deportation. Maria has applied for a U-Visa, a special visa for victims of crime. Only 10,000 U-Visas are available each year.

Defense attorney Herman Little stands in front of the Mecklenburg County Courthouse. Little said he watched helplessly as his client, an undocumented immigrant and victim of domestic violence, was arrested by ICE inside the courthouse last July. "If you can't find justice here," he said, "Where can you find it?" Hannah Rappleye / NBC News

Albence said he was not directly involved in the case but that Maria had appeared in court that day as a criminal defendant and therefore was subject to enforcement actions under the agency's policy. ICE spokesperson Bryan Cox said that Maria met "the threshold to be considered a public safety threat by definition of the charges."

However, neither Albence nor an ICE spokesperson would elaborate on how agents learned of Maria's case, saying that the agency does not disclose investigative tactics.

"When an individual gets arrested, their fingerprints are run and we get information on who they are, what their record is and what they are being charged with," Albence said. "She was arrested and charged with criminal violations … That is how the individuals come to our attention."

But Maria was never arrested, nor fingerprinted by the police. She appeared in court that day in response to a summons.

Diefenderfer said she suspects ICE acted on a tip from Maria's alleged abuser.

"It actually doesn't make sense how else ICE would have known she was there unless ICE is combing through criminal dockets at the Mecklenburg County Courthouse," Diefenderfer said. "I don't think they have time to do that.…It makes sense that someone tipped them off."

Maria's son, a victim who was not criminally charged, was also arrested.

Said Albence, "Individuals here in the country illegally don't get to choose whether or not they get to be arrested."

Diefenderfer said such uncompromising policies have forced her to change her message to the undocumented victims of domestic violence she serves. "Our message is scarier now," she said.

"Now I have to actively inform clients, 'I cannot guarantee that you will be safe,'" she said. "'If you don't report to the police, then you have no shot of seeking justice against your abuser. But you have to accept the risk that something might happen.'"

On a recent afternoon in a quiet park in Charlotte, as she watched her toddler play on the grass, Maria said she remains hopeful, despite her family's uncertain future. The assault charge against Danny was dismissed after he completed a diversionary program.

"Sometimes things happen without you wanting them to," Maria said. "We have dreams and sometimes they are broken, not because we want them to be, but because of adverse situations. If I have to return to Colombia, I will do so with my head held high, because I have nothing to fear. I have done nothing wrong."

"I will keep fighting for my dreams, because that is why I came," she added.