UPDATED 02/10/11 6 a.m.

MARKHAM, Ill. (WBBM/CBS) — Twin brothers charged last year with forcing young women to perform sex acts for money in the south suburbs will be going to prison, the first people in Illinois convicted of human trafficking.

LISTEN: Newsradio 780’s Steve Miller reports

Tyrelle and Myrelle Lockett, 18, of Dolton, pleaded guilty Tuesday to Class 1 felony charges of trafficking of persons for forced labor or services, and were sentenced by Judge Frank Zelezinski to four years in prison, a release from the Cook County State’s Attorney’s office said.

Police arrested the brothers last year after an undercover operation revealed they were forcing young women, including one underage girl, to perform sex acts with men for money. As part of the operation, Cook County Sheriff’s officers met with Tyrelle Lockett at a Lansing motel after responding to an online ad.

According to prosecutors, the operation involved making motel reservations and taking photos of the victims for the ads they created and posted. Once the meetings were set, the victims would enter motel rooms and have sex with men while the defendants waited nearby to collect payment.

The victims in the case told investigators both brothers beat and threatened them if they did not perform the sex acts. The brothers also kept control of all of the money the victims earned, the release said.

The victims in this case, a 17-year-old girl and an 18-year-old woman, were not charged. They were referred to the Salvation Army’s STOP-IT Program, which offers psychological and medical treatment, educational services and vocational training for victims of the sex trade, the release said.

In 2010, State’s Attorney Anita Alvarez created a Human Trafficking Initiative to combat the escalating incidents of sex trafficking and underage prostitution. Specially trained prosecutors work with local, state and federal law enforcement entities to investigate and prosecute cases.

Cook County Assistant State’s Attorney Lou Longhitano says the scope of human trafficking is broad and shocking.

“We’ve got sort of a perfect storm taking place here in Chicago,” he said.

In some respects, Chicago is a highly desirable site for the human trafficking trade, Longhitano said.

“We are a tour city for tourism, we’re a transportation hub, and we’re a conference and convention center,” he said.

And who are the humans who are being trafficked and forced into prostitution?

“There are kids, and those are the victims of human trafficking just as much as the faceless individual that you can imagine from halfway across the globe,” Longhitano said.

Most of the victims prosecutors see are from the area, and between the ages of 12 and 17.

The conviction of the Lockett brothers was the first in Illinois for human trafficking, officials said.

The Sun-Times Media Wire contributed to this report.

Watch & Listen LIVE