MIAMI -

A wave of Eastern Europeans and Chinese migrants involved in organized crime has changed the face of the commercial sex underworld in South Florida, an investigation looking at trends nationwide reported.

While street walkers who are selling sex acts in neighborhoods like Edgewater, Liberty City and Overtown for about $15 are often drug-addicted, the majority of "high-end" prostitutes -- charging up to $1,000 per hour -- are from countries like Russia, Ukraine, Croatia, and Albania.

The study by the Urban Institute's Justice Policy Center analyzed trends in the size and structure of of the underground commercial sex economy in eight cities, including Miami. For about three years, researchers interviewed law enforcement officers, pimps and prostitutes.

"Five years ago, we used to have mostly minors working the tracks, which really doesn’t happen as much anymore ... once we see something, we’ll start hitting it really hard, and then they’ll change the way they’re doing things," said a Miami police officer who assisted in the study funded by a $500,000 grant from the Department of Justice.

The most popular places to pay for sex in South Florida are erotic massage parlors. The Chinese operate the majority of them. And the owners -- who usually run several locations across Miami-Dade -- charge a "house fee" to rent a room and charge separately for sexual activity. The women take the tips.

This map shows the abundance of locations:

There are a few erotic massage parlors in Miami Beach that have caught the eye of police. They employ light-eyed, thin and tall eastern European women who may be part of a larger prostitution network. They usually targets tourists.

"They are also hitting the clubs on Miami Beach," Miami police officer said. “They just go from club to club looking for dates. Usually their pimp is close by – sort of kind of doing the street walking mode."

Escorts with or without pimps usually use internet-based advertisements and charge from $150 to $300. Some pimps operating in circuits in cities like Atlanta, New York and Las Vegas use the internet to promote the women.

"We have found that a lot of our pimps used to be ex-drug dealers and are now moving into pimping out girls. It’s more lucrative and harder to get caught, more prone to get caught dealing drugs," police officer said.

With the dramatic surge of demand for synthetic drugs such as amphetamine -type stimulants, the evolution of the international drug trade has changed. Some synthetic drug smugglers are coming from cities like Amsterdam, Brussels, Frankfurt and Paris.

There are pimps in Miami Beach who have a "wolf pack" mentality.

"They party together, go to the beach together, go to the club together, and have the girls outside when they go inside, have the girls come inside … I don’t know if it’s so much a network as a social network," a police officer interviewed for the study said.

Eastern Europeans linked to "organitzatsja," "mafiya," or "bratva" criminal world control the "high-end"escort network. They charge from $600 to $1,000 per hour, according to the investigation. Miami police usually assist other agencies with surveillance during undercover operations.

"Now you’re doing more wiretaps, following the money, doing a money laundering case to try to tie into an organized crime," a police officer said.

While online advertising is most popular on sites such as Craigslist, Backpage or Ero, the report found minors were moving from the streets to seeking shelter in strip clubs and topless bars.

In a recent case involving Club Madonna in Miami Beach, a 13-year-old girl said the club administrators never asked for her identification so she could strip at the club. She also said that during the Christmas break she was forced to have sex for $80 in a house in Little Haiti. 

Police said Miami's sex trade is "on a circuit" with major cities including Atlanta, New York, Dallas, Houston, Las Vegas, Orlando, Jacksonville, Seattle, and cities in California.

In the recent case of Kimberly Agorilla, 26, pimp Demetrick Cooks, 27 abducted her from a strip club in Orlando and forced her to travel to Las Vegas, Atlantic City and Hawaii.  Police arrested her and Cooks in Miami Springs.

In brothels in South Miami-Dade, Homestead and Florida City, the clients are often migrant farm workers paying about $25 for 15 minutes. The Mexican drug cartels smuggle the women and girls from Mexico, Honduras, El Salvador and Guatemala.

Miami prosecutors have taken down brothels involving Mexicans that traveled through New York, Texas, Georgia and Florida.

Some of the women and girls are forced to work in the sex trade to pay off their smuggling debt, but once the debt is paid, some of them choose to stay. In a world of extreme cruelty, coercion through psychological, physical and emotional abuse is often involved.

"They know how to make money now so they do it voluntarily," a Miami police officer said. "They’re much older now, not very attractive. It’s kinda like this is all they got."

Read the 2014 research report released in March