A 4-year-old boy’s ongoing care for stage 4 kidney cancer was interrupted when U.S. Immigration and Customs Enforcement officers illegally deported him, his sister and mother “without even a semblance of due process,” attorneys for the family say.

Though they are U.S. citizens and were born in Louisiana, the boy and his 7-year-old sister were deported to Honduras along with their 25-year-old mother, who is a Honduran citizen, on April 25, according to a federal lawsuit filed in the Middle District of Louisiana on July 31. The filing uses pseudonyms for the family, referring to the brother and sister as Romeo and Ruby and their mother as Rosario.

Before their deportations, Romeo, now 5, was receiving “life-saving” treatment at a New Orleans children’s hospital for his “rare and aggressive form” of cancer, following his diagnosis at age 2, a complaint says.

“As a direct consequence of ICE’s unlawful conduct, Romeo was deprived of much-needed continuity in his treatment, and he has faced substantial health risks due to his inability to access emergency specialized care and the routine critical oncological care that was available to him in the United States,” his family’s attorneys wrote in the complaint.