The Edward T. Gignoux U.S. Courthouse building in Portland as seen in this March 20, 2018, BDN file photo.

A husband-and-wife duo ensnared female Chinese tourists in an oppressive sex trafficking ring, locking down at least two Portland homes as prostitution dens for their enterprise, federal prosecutors say.

Sou Chao Li, 37, and Derong Maio, 37, of Concord, New Hampshire, face multiple charges of conspiracy to engage in interstate transportation and travel for prostitution, sex trafficking by fraud and coercion, and interstate transportation for prostitution, according to a Thursday afternoon announcement by the U.S. Attorney’s Office.

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A grand jury indictment for the husband and wife was unsealed on Thursday, according to the U.S. Attorney’s Office.

The indictment alleges that Li and Maio recruited Chinese women who came to the United States on tourism visas, then put them to work having sex with clients in homes and hotel rooms in Maine, Vermont and New Hampshire.

In addition to a number of inn and motel rooms, Li and Maio rented residences at 5 Verrill St. and 977 Brighton Ave. in Portland for weeks in 2016 and operated the locations as “prostitution houses,” the indictment claims.

[Boston man who forced Maine women to work as prostitutes gets 17 years]

The defendants and their co-conspirators advertised the women for sex on the website, and controlled the victims by withholding food, clothes, documents and other necessities, according to prosecutors.

Daphne Hallett Donahue, attorney for the husband, said he was “bewildered and exhausted” when she met him in court after his arrest Tuesday. She said she couldn’t yet comment on details of the case.

An attorney for the wife declined comment.

The two defendants pleaded not guilty to the crimes on Thursday, according to the Portsmouth Herald.

The sex trafficking charges carry maximum sentences of life in prison, according to the U.S. Attorney’s Office.

Information from the Associated Press was included in this report.

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Seth Koenig

Seth has nearly a decade of professional journalism experience and writes about the greater Portland region.