A Marine vet with post-traumatic stress disorder was held for three days by Immigration and Customs Enforcement (ICE) for possible deportation before authorities realized he was a citizen born in Michigan, lawyers said Wednesday.

Jilmar Ramos-Gomez, 27, of Grand Rapids, was deemed "a foreign national illegally present in the U.S." by ICE and was detained on Dec. 14. He was released on Dec. 17 after records demonstrated he was an American citizen.

"Why did they think he was a noncitizen? Did they get him confused with someone else? Who knows," American Civil Liberties Union (ACLU) attorney Miriam Aukerman said. "This is an individual who's incredibly vulnerable with a mental illness."

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Ramos-Gomez was apprehended by police after being accused of trespassing and damaging a fire alarm at a Grand Rapids hospital on Nov. 21. He was placed in Kent County jail, and was set to be released on Dec. 14 after reportedly pleading guilty to the charges against him. At that point, he was turned over to ICE and taken to a detention center 70 miles away, though he reportedly had his U.S. passport with him.

Kent County Deputy Sheriff Chuck DeWitt shifted the blame when contacted for a comment. "Once he was released from our custody, he was under the domain of ICE," he said. "Where they take him is their process. Our procedures were followed."

Ramos-Gomez is undergoing mental health treatment, so little is known about the time he spent in ICE custody. However, Aukerman called the treatment of the veteran as "appalling."

Robert Kessler, an immigration lawyer based in Grand Rapids, was familiar with Ramos-Gomez because he aided in securing temporary residency for the veteran's mother, Maria Gomez. When Ramos-Gomez's mother told him what happened to her son, he took action.

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“I immediately called ICE and shouted at them,” he told The Washington Post. “And they called me back and said, kind of, ‘Oops, yeah, come and get him.’ They didn’t say, ‘Our bad,’ but kind of implied that.”

He added that the situation was a clear example of racial bias. “I think it’s racial stereotyping. And it should have been evident that he had pretty significant mental health issues."

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Ramos-Gomez served in the Marines from 2011-14, during which time he received accolades including a national defense service medal, a global war on terrorism service medal, an Afghanistan campaign medal, and a combat action ribbon. Upon returning home, the ACLU says he was "a shell of his former self," and suffered from PTSD as a result of things he'd seen in combat. According to his family, he often has episodes in which he experiences dissociative amnesia - disappearing for periods of time with no recollection of where's been.

The Associated Press contributed to this report.