CHICAGO (CBS) — An immigrant mother whose son has spent nearly a month away from her in Chicago after they were separated at the border is fighting to be reunited with her boy as she waits for an asylum hearing in Massachusetts.

Lidia Souza and her 9-year-old son, Diogo, crossed the border into the U.S. last month, after fleeing their homeland of Brazil, fearing for their lives.

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Although Lidia passed an initial screening, she was prosecuted for crossing the border illegally under the Trump administration’s “zero tolerance” immigration policy, and she and her son were separated.

Lidia eventually was released from federal custody, and is staying with her family in Boston while her asylum application is pending. Her son, however, was brought to Chicago after the two were separated.

So Lidia and her attorney, Jesse Bless, have flown to Chicago, where Bless plans to file a lawsuit seeking to have mother and son immediately reunited.

Diogo turned 9 years old last week, while separated from his family, at a facility run by the Office of Refugee Resettlement.

Bless brought a few small stuffed animals to give to Diogo if he and Lidia are given a chance to see him on Tuesday. He is seeking an emergency hearing in an effort to have Diogo and his mom reunited as soon as possible so they can go back to Boston together.

“It’s just about this boy, whose safety is at risk, who’s told his mother he does not feel well. They cannot communicate more than 20 minutes a week. He celebrated his birthday alone, and today is day 27 without him and his mother together,” Bless said. “They fled persecution only to be persecuted.”

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Lidia Souza and her son, Diogo. (Photo supplied to CBS)

Speaking Portuguese, Lidia thanked God and all the people who have helped her during her ordeal, saying through tears she just wants to go back to Boston with her son.

Bless said, at the very least, they want federal authorities to arrange a face-to-face meeting between Lidia and Diogo.

He also produced a federal document clearing Lidia to fly to Chicago to “pick up a minor child from the Office of Refugee Resettlement.” He said a lack of fingerprints had been a sticking point with federal authorities, but the document clearing her to pick up her son has her fingerprint, so that will lead to the breakthrough they need to have Lidia and Diogo reunited.

Statement from Jesse Bless, Attorney for Lidia Karene Souza and Diogo Magno de Oliveria Filho:

“After multiple conversations with officials, Lidia Karene Souza and I were allowed to see and spend approximately one hour with her 9 year old son Diogo Magno de Oliveira Filho today. The meeting took place at a separate location from the facility in Chicago where he is being detained.  It was an extremely emotional meeting and even more emotional parting — for a second time — as officials would not allow the child to be released into the custody of his own mother.

As a result of this extremely disappointing outcome, we have filed for an emergency hearing and continue to litigate this case.  This was a devastating outcome for both Lidia and her child, but we remain hopeful that officials will reverse this decision and release him to his mother very soon.

I want to reiterate that Lidia followed all laws and proper channels to enter this country and apply for asylum.  Despite this and having been released on her own recognizance, her child has been taken from her twice and held at a detention facility.”

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CBS 2’s Mike Puccinelli and Roseanne Tellez contributed to this story.