MINNEAPOLIS – Sex traffickers use violence to a degree that surprised researchers who released a preliminary study Wednesday of the structured business strategy behind the juvenile sex trade in Minneapolis.

The 118-page report, "Mapping the Market for Sex With Trafficked Minor Girls in Minneapolis," aimed to examine the trade as an industry and found sophisticated systems to recruit, retain and market victims to meet demand.

Researchers examined nearly six years of Minneapolis police and Hennepin County district court records during the study, which was funded by the Women's Foundation of Minnesota and the University of Minnesota Children, Youth and Family Consortium. They also looked at seven years of media reports and interviewed 89 people who work directly with victims.

"I was surprised by how organized and strategic the use of violence in these trafficking operations really is," said Lauren Martin, director of research at the university's Urban Research Outreach/Engagement Center, one of the study's authors. "It's strategic and has a purpose in developing girls as a product for sale. . It degrades the girls' sense of themselves and creates an objectification where girls devalue themselves."

Although many court documents didn't necessarily track violence in such cases, researchers still found evidence of pimps using severe violence and threats against 34 percent of victims, the Star Tribune reported.

The study supports long-held notions about the juvenile sex trade, including:

— Police data show the average age of victims was 15 to 16 for all races except Latino victims; for that group, the average age was 13.

— Sex buyers come from all communities, with the largest portion being white.

— Vulnerable juveniles were targeted, sometimes by peers, in places such as schools, parks, malls, bus stops, parties, treatment facilities and juvenile detention centers.

— There was an over representation of communities of color as facilitators and victims. Poverty-stricken neighborhoods were among the hardest hit.

In a statement Wednesday, U.S. Sen. Amy Klobuchar, D-Minn., who has introduced legislation to combat sex trafficking, said the report "is more hard evidence that sex trafficking is not something that only happens half a world away — it's happening here in our own backyards and we need to take action."

The study suggest several prevention strategies, including changing social culture among males, raising awareness about peer recruiting and strengthening opportunities for personal and professional development for young people 12 to 17 years old.