Kansas City, Mo. ? One of 12 people charged in a human trafficking ring has pleaded guilty in federal court to one count of forced labor trafficking.

Prosecutors on Wednesday said 24-year-old Alexandru Frumusache, of Moldova, obtained “labor services of a person by means of serious harm and threats of serious harm to that person or another person.”

Eight Uzbekistan nationals and four other people were charged in May in the largest human trafficking case ever prosecuted in Kansas City.

Federal officials say the operation turned workers into slaves, fanning them out to housekeeping jobs in 14 states. Officials allege the ring operated from 2001 until this spring.