A Gwinnett County woman was sentenced to nearly 12 years in prison Thursday after being convicted of human trafficking and forced labor involving two Nigerian teenagers who were kept captive and made to work as house servants and nannies for her daughter.

"They were turned into virtual slaves, worked 20 hours a day and cut off from the outside world," said U.S. Attorney Sally Quillan Yates, whose office prosecuted the case. "Once she got them here they weren't only enslaved but ... every step she took was done to strip them of any human dignity."

Yates described the case of Bidemi Bello, 42, as one of the most egregious examples of human trafficking she had prosecuted in Atlanta, and unusual because it involved enslaved house servants and encompassed what  the defense argued were cultural norms in Bello's home country of Nigeria.

Federal public defender Suzanne Hashimi asked U.S. District Judge William S. Duffy Jr. for leniency and a nearly two-year reduction in the sentence because she argued Bello had also been abused as a house servant when she was growing up.

“We often forget where our clients come from," Hashimi said. "They didn’t appear on the street as mean people. ... We can have compassion for her victims as well as her."

Bello also addressed the judge. Dressed in an orange jump suit, the once successful businesswoman wept and told the judge she had harmed not only the two victims but also her only daughter, who moved to Nigeria. “My actions have cost my daughter the opportunity of being raised here," she said. "There is just so much shame.”

She turned to the two victims, who were seated in the courtroom.  "I'm sorry," she said.

The judge noted that Bello had been educated in London and had become affluent, owning large homes in Suwanee and Sugar Hill after becoming a U.S. citizen. Instead of using her wealth to hire servants, she instead had imported two girls from Nigeria and abused them, Duffy said.

Prosecutors at trial painted a picture of abuse that was sadistic as well as exploitative: Bello made the girls bathe from a bucket in which they also washed clothes and eat spoiled and moldy food after they had served her dinner.

“You made a comment that you were alone and at the mercy of other people,” Duffy said before imposing sentence.  “I wondered what it was like in your home. ... There wasn’t much mercy."

Duffy sentenced her to 140 months in prison and ordered her to pay $144,200 in restitution to the victims.

The girls, identified in court by the aliases Laome and Dupe, are both now 27. They said they had to respond to Bello's demands immediately and at all hours or risk a beating.

"When she called me and I didn't answer in time, she would slap me," Laome said after the sentencing.

Bello recruited Laome, then 17,  in 2001.  She  escaped in 2004, she said, with the aid of a woman who learned of her predicament. Bello returned to Nigeria to recruit 19-year-old Dupe later that year, authorities said. Dupe said she escaped in 2006 by taking a cab to a Marietta Methodist church, where she found protection.

Bello left the United States during the investigation, and when she re-entered at the Houston airport she was arrested. She was indicted in September 2010.

Bello became a naturalized U.S. citizen in 2004 but will lose her U.S. citizenship.

Laome and Dupe are now living and working in the United States on visas. They were pleased with the judge's sentence.

"I'm just happy she is going to jail and hopefully to change," Dupe said.