MARTINEZ (CBS SF) — A Contra Costa County couple has been charged with criminal labor trafficking, extortion and conspiracy for allegedly recruiting a nanny from overseas and forcing her work as a virtual slave in their home, authorities said Monday.

Ijeoma Chukwunyelu and Nnamdi Onwuzulike of Brentwood made their first court appearance last month and entered pleas of not guilty in the county’s first criminal labor trafficking case, the district attorney’s office said.

The couple allegedly recruited a woman from Nigeria to be a nanny for their children, instructing the victim to obtain her passport and visa fraudulently and claim she was coming to California for three weeks as a tourist to attend the wedding of her son and the defendants’ daughter, according to the DA’s office.

When the victim arrived in April 2017, Chukwunyelu and Onwuzulike took her passport and visa and forced her to perform work beyond what she was hired to do, the DA’s office said. According to the complaint, the victim was required to sleep on the floor of the children’s room so she could care for them round the clock, cook for the entire family and clean their five-bedroom house for no additional wages above the $150 a month she was being paid.

The nanny also was not given any days off and was never paid overtime for the additional hours she worked, the DA’s office said. In addition, Chukwunyelu and Onwuzulike continued to employ the woman even after her visa expired, making the victim an even more vulnerable worker fearful of deportation.

“As the COVID-19 pandemic causes massive job losses and severe economic instability, California workers are more vulnerable than ever to exploitative employment practices,” said Contra Costa County District Attorney Diana Becton in a prepared statement. “Our collaborative efforts on this investigation led to a successful filing of this case. I am proud to work with our partners at all levels of government to protect workers and seek justice for those harmed by predatory behavior.”

The investigation was a joint effort of the Brentwood Police Department, the Contra Costa County District Attorney’s Office, Homeland Security Investigations, the United States Department of Labor, and the California Department of Industrial Relations/Division of Labor Standards Enforcement and the Victim Witness Assistance Program within the DA’s office.

The investigation began when American Medical Response (AMR) personnel recognized a victim in need of assistance and connected her to resources that could help her.

“The experience of this domestic worker represents countless more who are preyed upon because of economic desperation. These criminal acts are not only illegal but immoral,” said California Labor Commissioner Lilia Garcia-Brower in a statement. “Human trafficking is modern-day slavery, and we are committed to stopping it by partnering with agencies to eradicate this horrific crime.”

Any person who thinks they may be a victim of labor trafficking in Contra Costa County can make a report to the DA’s Office Human Trafficking Tip Line at 925-957-8658.