Migrant parents who were separated from their children by U.S. Customs and Border Patrol arrive at the Annunciation House migrant shelter after being released from U.S. Customs and Border Protection custody on Sunday. It is not clear how they will find their children, who are in the custody of a different federal agency. (Joe Raedle/Getty Images)

A visibly upset U.S. Sen. Elizabeth Warren visited the detention center where the Trump administration said separated migrant families would be reunited and deported and said she’d seen no evidence that the process was underway.

The Department of Homeland Security said in a statement late Saturday that U.S. Immigration and Customs Enforcement has “dedicated the Port Isabel Service Processing Center as the primary family reunification and removal center for adults in their custody.”

But Warren (D-Mass.) spent two hours inside the facility speaking with immigration officials and detained immigrant mothers Sunday night and said there were no reunifications to report. She said she spoke with nine women: “In every case, they were lied to. In every case, save one, they have not spoken with their children. And in every case, they do not know where their children are.”

“It’s clear,¨ Warren said. “They’re not running a reunification process here.”

Advocates interviewed outside the locked gates earlier in the day described desperate parents giving up their hopes of asylum to get their children back in their arms more quickly. They also noted that the Port Isabel facility is not set up to house minors.

“This is the most inefficient, preposterous system that I have ever encountered,” said Sirine Shebaya, a Washington-area civil rights lawyer who had flown to South Texas with a team that spent Friday and the weekend interviewing parents.

“We have people in there who are considering not continuing on with really strong asylum claims because they think they’ll get reunited with their kids faster if they give up their claim,” Shebaya said. “That’s just wrong.”

The Trump administration said it was taking steps to return some 2,053 “separated minors” who had been taken into custody as part of Trump’s border crackdown, after the government elected to criminally prosecute all adults caught crossing the border. The statement said 522 children had been returned as of Saturday, and another 16 were expected to be with their parents within 24 hours.

The parents — many of whom say they are seeking asylum and fleeing gang violence or domestic abuse — have typically pleaded guilty to entering the country illegally and been transferred to adult immigration jails run by Immigration and Customs Enforcement to await deportation. Their children, meanwhile, are sent across the country to shelters run by the Department of Health and Human Services, or placed by the federal agency in foster care.

“The United States government knows the location of all children in its custody and is working to reunite them with their families,” the statement read. “This process is ­well coordinated.”

Shebaya said Port Isabel, a remote, 1,200-person facility surrounded by a wind farm, a wildlife refuge and miles of empty prairie crawling with coyotes, falcons and bull snakes, “seems to be at capacity” and is “not equipped to hold children.”

“That kind of begs the question,” she said. “ ‘Where are they going to put the children?’ ”

A senior administration official, who declined to be identified, said officials never intended to send busloads of children to Port Isabel for a massive reunion.

Instead, the official said, they plan to reunite families on an individual basis once a parent has lost his or her deportation case. Parents may ask for their children to join them so that they can be deported together, the official said.

Shebaya said most migrants she interviewed were on a “fast-track” deportation process for recent border crossers, which is delayed only if they express a fear for their lives. Such a declaration triggers an interview to see whether they have a valid asylum claim. If they do, they could have a court hearing. If they don’t, they could be deported, with limited avenues to appeal that decision.

Eileen Blessinger, a Virginia immigration attorney, estimated that 25 percent of the roughly 100 parents she and two colleagues interviewed at Port Isabel had been able to speak to their children as of Sunday afternoon.

Some parents had special-needs children they had not heard from in weeks, including a woman who said she had not heard from her deaf and mute child. When one woman finally heard from her 7-year-old, the child said, “You don’t love me, you left me,” the mother told Blessinger.

One father said in a telephone interview from inside Port Isabel that he hadn’t spoken to his 13-year-old daughter since they were separated almost two weeks ago. “I have no idea where she is, if she’s eating, if she’s scared,” said the 37-year-old, who asked to go by his middle name, Roel, because he faced death threats back in Honduras. “All of us parents here are so worried.”

“She is the only child I have,” he said. “I’ve cried many times in here. Many times.”

Sophia Gregg, another Washington-area immigration attorney working inside Port Isabel, said the group had spoken to parents who had experienced horrible trauma on the way to the United States, yet they were focused on the whereabouts of their children.

“We’ve heard stories of women being held captive, enslaved in cartel homes,” she said. “And that’s secondary to that they don’t know where their child is.”

Natasha Quiroga, another attorney in the group, said one father who hadn’t spoken to his daughter in more than a month became so desperate he wrote her a letter, telling her to self-deport.

One mother who said she had fled threats from drug traffickers in Honduras gave Blessinger a letter to deliver to her 7-year-old boy, with whom she hadn’t spoken to since they were separated two weeks ago. The handwritten letter is addressed to “My reason of my life.”“Be strong and fight. Don’t get sad,” it says. “Your mommy loves you and they will never separate us again.”

Ruby Powers, an immigration attorney from Houston, said a Honduran client of hers at a privately operated ICE facility in Livingston, Tex., was not allowed to speak to his 6-year-old daughter for three weeks.

Only after he signed a request for voluntary removal was he allowed to speak to the child, who has asthma and was being held in a shelter in Arizona. Powers, who is now trying to rescind his request, said the 24-year-old father had fled violence in Honduras, where his cousin had been killed.

The Saturday night statement, jointly issued by the Department of Homeland Security and HHS, said ICE will implement a system for tracking separated family members and reuniting them before their deportation as a unit. Parents will begin receiving more information about the whereabouts of their children and telephone operators will provide more frequent communication.

“There will be a small number of children who were separated for reasons other than zero tolerance that will remain separated,” it said. “Generally only if the familial relationship cannot be confirmed, we believe the adult is a threat to the safety of the child, or the adult is a criminal alien.”

In El Paso, a DHS bus pulled up outside Casa Vides, a shelter for migrants, on Sunday afternoon and disgorged about 30 people who had been held on misdemeanor immigration charges until the charges were dropped Thursday and Friday. The migrants will get access to legal help, focusing on finding their children, said Ruben Garcia, executive director of Annunciation House, the nonprofit that runs the shelter.

They are free on their own recognizance while their immigration court proceedings continue, and some will probably wear ankle monitors. It remains unclear how the reunification process the federal government announced Saturday night will be implemented for this group. Garcia said he had been told the parents had to call an 800 number that the government has provided in recent days. Taylor Levy, the group’s legal services director, said if people get through at all, they are told that someone will get back to them several days later.

Garcia and Levy said the reunification process is further clouded by a new agreement that calls for the Office of Refugee Resettlement, which cares for and attempts to place minors apprehended at the border, to share information with ICE and Customs and Border Protection. Anyone seeking to take custody of a child from ORR must agree to submit fingerprints of all adults in the household to ICE, a frightening prospect for many undocumented immigrants.

Levy criticized President Trump for his tweet earlier Sunday that said when somebody arrives at the border, they should be immediately deported without legal proceedings.

“That is not what our country stands for,” she said. “These people are fleeing for their lives, they are refugees, they are not economic migrants. The vast majority of them are coming here because they have no other option and they want to survive, and they want their children to survive. And they have every right under United States laws and under international treaties to fight their cases and be given the process that is due.”

Sacchetti reported from Port Isabel. Moore reported from El Paso. Nick Miroff contributed to this report.