(CNN) Peter Sean Brown was born in Philadelphia. He'd only spent a day in Jamaica once on a cruise.

But even though he repeatedly told authorities in Monroe County, Florida, that he was a US citizen, according to a federal lawsuit filed Monday, they held him in custody and threatened that he was headed to a Jamaican prison, citing a request from Immigration and Customs and Enforcement.

Now, more than seven months after he allegedly ended up in an ICE detention center, Brown, 50, is suing the Monroe County sheriff, alleging he was illegally detained.

Peter Sean Brown was detained in April.

Monroe County Sheriff's Office spokesman Adam Linhardt and ICE spokeswoman Dani Bennett declined to comment, saying their agencies don't comment on pending litigation.

The complaint filed by a coalition of immigrant rights groups Monday in US District Court for the Southern District of Miami details Brown's allegations about his April 2018 detention and its aftermath.

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