LOS FRESNOS, Texas — Near the end of a two-lane stretch of road leading to the Port Isabel Detention Center, attorney Sirine Shebaya is choking back emotion over the lengths mothers and fathers are going to be reunited with their children.

"We have people in there who are considering not continuing on with really strong asylum claims," she said stopping to catch her breath as the emotion breaks through, "because they think that maybe they will get reunified with their kids faster if they give up their claim. That's just wrong."

As mothers and fathers wait in the secured, remote detention center amid the chaos of the Trump administration's "zero-tolerance" policy that led to forced separations of children from their parents, attorneys like Sheboya and others have been thrust into doing the detective work of helping the parents learn the whereabouts of their children and giving parents hope that they will be reunited.

Shebaya, senior staff attorney for Muslim Advocates whose work often overlaps with immigration, said she didn't think the immigration system was necessarily fair and just in the Obama years, but she had "never seen anything like this."

"The immigration system has been harsh and enforced in a manner that lacks compassion, but I've never seen a volume of people who are punitively separated from their children for no reason," she said.

Sen. Elizabeth Warren, D-Mass., spent two and a half hours in the Port Isabel Detention Center on Sunday night. After the visit, she told reporters stationed outside the center that officials of Immigration and Customs Enforcement told her that the center isn't where parents and children will come together as federal officials have said.

"The [immigration] officials made clear this is not a reunification center. There will be no children brought here. There will be no families brought together in this place," Warren said. "All that's happening here is the detention of mothers and fathers who lost their children."

The Department of Homeland Security said late Saturday in a "fact sheet" that it has a well-coordinated process of reuniting families. But by Sunday, Trump was calling for all migrants to be deported without trial.

Warren said no officials at the detention center could articulate a plan for reunifying families.

"The ICE officials that we saw speculated that each of these parents would be released at some point and that the children, wherever they are, would be sent to that place individually ... one at a time, wherever that parent has been released to," she said.

A Trump administration official pushed back on Warren's account Monday morning, saying "reunifications are happening for the purposes of removal at Port Isabel."

The official said parents are given the option to take their child with them upon removal and the child is then transferred to Port Isabel for the deportation.

The official said the reunifications at Port Isabel were already happening and would continue going forward, but did not have numbers on how many had already happened.

As for parents who choose to continue fighting claims for asylum or other types of immigration relief, reunification will depend on if the parent remains in detention, the official said. If a parent remains in detention throughout their case, the children will remain in the custody of the Department of Health and Human Services, according to the official.

Parents who are released into a monitored supervision program are allowed to apply to sponsor their own children, the official said.

But on Sunday, a Texas charity that houses migrants said that 32 parents who were separated from their children were released into their care and they do not know where their children are or when they will be reunified.

"We do not know exactly the people who are coming to us. We do not know where their children are," Taylor Levy, legal coordinator at the Annunciation House said at a news conference.

Rubén Garcia, the group's director, said he was told the parents are only being given a 1-800 number to call and try to find and speak with their children. Annunciation House is providing shelter and legal services for the parents.

Levy added that sometimes parents are on hold for more than an hour after calling that number and are told it will take days to speak with their child, if someone answers the phone at all.

"Even when we get these people, there’s no magic bullet that we’ll be able to do to figure out where their children are instantly," she said.

Attorneys have become a lifeline for migrants in detention, responding as would clergy to a disaster or tragedy, as the legal labyrinth of immigration has become more complicated.

Although many are accustomed to the immigration system's complexities, attorneys are finding the situation created by the Trump "zero-tolerance" prosecutions full of never-before-seen hurdles and restrictions that hamper their access to children and parents and are making their work to ensure those with valid asylum and other claims get to stay more difficult.

Ali Rahnama, an immigration attorney from Washington who works on public policy and high impact litigation, said he woke up last Monday and felt he needed to be on the border. He found a private donor to pay for him and a few colleagues to fly to the border.

Rahnama said he and other attorneys expected ICE would have access to a database that would have information on where each child is, but no such database seems to exist.

"They are asking us (and advocacy groups) to give them that information," Rahnama said.

An immigrant from Iran, Rahnama said he came alone to the U.S. and it was not easy to immigrate here, but he said he feels fortunate he is not going through what the migrant parents he has interviewed are going through.

"We have men and women saying, 'My 5- and 6-year-old was holding my leg and was taken away,'" said Rahnama, who visited parents and guardians being held in the Port Isabel Detention Center. "They go to court and are told their child will be there when they come back, and they come back and there is no child," he said.

The facility is obscured by foliage and can't be seen until about halfway up the road leading to it, where officers stand guard, stopping journalists and others without prior permission to enter. Families who have appointments to visit with people in the detention center drive in and out.

Warren said the complex "feels like a prison." It is surrounded by concertina wire and double fenced with the immigrants kept under lock and key.

Ofelia Calderon serves on the board of the Dulles Justice Coalition, a group of attorneys that formed when President Donald Trump signed an executive order that initially banned people from seven Muslim majority countries from obtaining visas to enter the U.S.

Calderon said in her interviews of 35 people over a day-and-a-half, all had had their children taken from them, and about 30 percent had made contact with their child. Of those able to contact their child, only some had a vague idea of the child's whereabouts and little information on the conditions of where the child was staying.

One person Calderon spoke to had a 10-year-old son who had been able to tell the parent "I think I'm in Miami," but little else.

She said she encountered several women who had been sexually assaulted, but even then they were more focused in the interviews on finding out about their children than on relaying their trauma.

"They are breaking down and saying, 'Where's my kid?'" Calderon said.

Warren said she spoke to nine mothers and none knew the whereabouts of their children or had spoken to them.

"They are crying, they are weeping," she said. "They have said they will do anything ... just, please, let them have their babies back."

Those who do have contact with their children get about one to two minutes on the phone with them, Calderon said. Some have found out where the children are through family back home. People in detention have to receive money from relatives to buy minutes on phone cards to speak with family members. The attorneys were uncertain whether the calls to their children were free.

The case of a 15-year-old boy who ran away from a shelter in Brownsville was not likely to ease fears of parents who have yet to connect with their kids. A source with direct knowledge of the situation told NBC News the child ran away from Casa Padre in Brownsville, Texas, run by Southwest Key.

The shelter had been in conversation with the man he calls his father, but there had been a discrepancy in a DNA test. Before things could be sorted out, the child left and is now in Mexico, according to the source. The man who the child said was his father is sending him money to return to Honduras.

The source said Southwest Key has 19,849 children in its care — of that number, 42 have left. The Department of Health and Human Services (HHS) did not return NBC News' request for comment.

Southwest Key said in a statement that it is a child care center and not a detention center. "If a child attempts to leave any of our facilities, we cannot restrain them," Southwest Key stated. "We talk to them and try to get them to stay. If they leave the property, we call law enforcement.

DHS said late Saturday that some of the more than 2,000 children — about 522— have been reunited with parents. Officials said Port Isabel would be its reunification center.

Sometimes it's not just children who attorneys have to locate, but some of the parents as well. Efrén Olivares of the Texas Civil Rights Project can no longer find three clients who were part of a group of five parents who complained in a petition filed with the Inter-American Human Rights Commission, part of the Organization of American States, about the child separations.

"They were either released to the U.S. with notice to appear (at a court at a later date) or were deported. We are looking diligently to contact them. We gave them a number and asked them to contact us if they were released," Olivares said. "We have not heard from them."