A man has pleaded guilty to federal charges for his role in a sex trafficking operation that coerced Chinese women into prostitution in New England.

Shou Chao Li appeared in U.S. District Court in Portland on Thursday. He and his wife, Derong Miao, were both indicted on a host of charges in 2018. She pleaded guilty to five counts last month and is awaiting sentencing. Court documents show the couple admitted that they rented two properties in Portland that were used for commercial sex, and they were involved in transporting at least four different women between New Hampshire and Maine for prostitution.

Li pleaded guilty to one count of conspiracy to engage in interstate transportation and travel for prostitution, as well as four counts of interstate transportation for prostitution. The prosecutor agreed to dismiss two counts of sex trafficking by fraud or coercion, one count of interstate transportation for prostitution, and one count that accused him of possessing the passport of one of the victims.

Li was 37 years old when he was arrested in 2018. Court documents filed so far contain few other details about the couple, but the sentencings could bring forth other facts about their lives. Those hearings have not been scheduled yet, but Li agreed not to appeal any sentence shorter than four years and three months. His wife made a similar agreement. The conspiracy charge carries a possible penalty of five years in prison; the interstate transportation charges, up to 10 years each.

Defense attorney Mingli Chen said he was glad Li decided to face the consequences of his actions, and he would ask for leniency in sentencing because his client accepted that responsibility by pleading guilty. He also said he is the eldest son in his family, and his aging parents will rely on him for their care.

“His family needs him,” Chen said after the plea hearing.

Assistant U.S. Attorney Darcie McElwee declined to answer questions about the case. Court documents do not identify any of the women who were exploited as part of the trafficking operation or say what happened to them after Miao and Li were arrested. None attended the court hearing.

A 2015 assessment published by the Maine Sex Trafficking and Exploitation Network estimated that there are 300 to 400 victims of sex trafficking in Maine every year. That assessment described the profile of a trafficking victim in Maine as a white woman between 14 and 30 years old, with a history of sexual abuse or domestic violence and a strong possibility of drug use.

The Immigrant Legal Advocacy Project does not comment on individual cases like this one, but senior staff attorney Kate Chesney said male and female immigrants can be vulnerable to trafficking for labor or sex. They might be relying on their trafficker for legal status or protection in the United States, and they can be isolated by a language barrier and a lack of connections in the United States.

“They’re criminal enterprises that are very skilled in making people not want to come forward, not even believe they’ve been trafficked, not believe they have any way to leave,” Chesney said.

There are two types of visas available to people who have experienced trafficking or other serious crimes, like domestic violence or sexual assault. Last year, the federal government approved more than 1,000 visas to victims of trafficking across the country, more than any other year in the previous decade. It granted another 10,000 for victims of other crimes, although Chesney said that number is a cap that Congress should increase because more than 160,000 applications are pending.

“It’s definitely a long road, and it’s not a fun process because you have to go into excruciating detail about the victimization,” Chesney said.

Both Li and Miao have been in federal custody since their arrests. During the hearing, he stood quietly and answered questions with the help of a Mandarin interpreter. It is not clear whether the conviction will have an impact on Li’s residency in the United States. One court document describes him as a Chinese national, while another indicates he is a naturalized American citizen.

As part of his plea agreement, Li agreed not to contest certain facts in a narrative filed by the government. Miao made a similar agreement. The document mentions other conspirators but names only the husband and wife, and it describes activities that took place in 2016 and 2017. It is not clear whether any other people have been charged in connection with the case.

The government says Li and his wife were living in New Hampshire when they participated in the trafficking scheme. They leased four residential properties, including two in Portland, that were used for prostitution. Miao allegedly used a social media platform called WeChat to talk to Chinese women about engaging in prostitution in New Hampshire and Maine.

The document says the women had mostly come to the United States on visas that did not legally allow them to work, and they hoped to find other jobs but were unable to repay debts associated with their travel. They spoke little or no English and had no other contacts in Maine or neighboring states.

The government says Li and Miao “benefited financially” from the scheme, and they also made payments to unnamed conspirators. Those conspirators posted ads online and made arrangements for commercial sex at the locations used or paid for by the couple in Maine, New Hampshire and Vermont. The document says Miao helped with transportation and other logistics needed to bring the women to New England from other states, and the couple moved the women between hotels and houses in New Hampshire and Maine. It ties them to four separate but unnamed victims.

“Beginning on about August 18, 2016, and continuing until at least October 30, 2017, on at least 33 occasions, the defendant and his wife leased, rented, or agreed to pay for the cost of identified locations (houses of prostitution or hotel rooms) in Maine, New Hampshire, and Vermont where identified Chinese females were actual or registered guests,” the document says.