HOUSTON (AP) — A Houston-area couple pleaded guilty on Wednesday to charges related to forcing a Nigerian woman to care for their five children and home without pay for two years, having her work nearly 20 hours a day.

Chudy Nsobundu, 57, and his 49-year-old wife, Sandra Nsobundu, recruited the woman in Nigeria with the promise of a $100 monthly wage, prosecutors said. Instead, authorities say they abused the woman physically and verbally while she worked at their home in the Houston suburb of Katy, denying her compensation or outside contact from September 2013 to October 2015.

Chudy Nsobundu pleaded guilty to visa fraud while his wife pleaded guilty to unlawful conduct with respect to documents in furtherance of forced labor, said U.S. Attorney Kenneth Magidson.

Attorneys for the couple didn't immediately return calls seeking comment on Wednesday.

The Nsobundus, who are naturalized U.S. citizens originally from Nigeria, will be sentenced on Jan. 4. They remain free on bond.

Sandra Nsobundu faces up to five years in prison, while her husband faces up to 10 years imprisonment.

According to court documents, the nanny would work every day from 5:30 a.m. to 1 a.m., couldn't take breaks and had to eat leftovers and not fresh food, including being forced to only drink milk left in bowls in which the children had eaten cereal. She also couldn't take hot showers.

Authorities said the Nsobundus prevented the nanny from leaving their employment by keeping her passport and by threatening her with physical and mental abuse.

The nanny reached out for help and was rescued following a tip to the National Human Trafficking Resource Center.

Prosecutors are seeking restitution in the amount of $129,108 to pay for back wages owed to the nanny, whose name has not been released by authorities.