( CNN ) -- A federal judge in Mexico has sentenced four people to a minimum of 16 1/2 years each behind bars for human trafficking , the Mexican attorney general 's office said Tuesday , marking a rare conviction in a country struggling to get a grip on the illegal trade . The investigation began because of a tip from the U.S. Immigration and Customs Enforcement ( ICE ) agency , authorities said . Agents rescued four women being forced to work as prostitutes in Miami , Florida , according to a statement from the Mexican attorney general 's office . An ICE spokeswoman said U.S. agents identified two of the victims in Miami and that the other two were identified by authorities in Mexico . Their children were being held in Tenancingo , a municipality in the southern Mexican state of Tlaxcala , and the women 's contact with them was conditioned on their sending money to their handlers , the statement said . On June 7 , 2010 , Mexican authorities raided the home in Tlaxcala , arresting the four suspects . Fausto Velazquez Zompantzi , Jaime Velazquez Zompantzi and Severiana Zompantzi Rojas were sentenced to 16 1/2 years in prison each for the parts they played in the crime . Jorge Velazquez Zompantzi was sentenced to 18 1/2 years . In addition to trafficking , he was also found guilty of possessing a firearm licensed exclusively to the military . The women 's children were sent to be with their mothers in the United States , according to the attorney general 's office . The statement said the case represents the first time the attorney general 's office of the Special Prosecutor for Organized Crime , also known as SIEDO , obtained a conviction and sentence for a human trafficking crime . Mexico , like many countries , struggles to investigate , prosecute and punish trafficking offenders . The U.S. State Department released its 2011 report on human trafficking Monday , assessing efforts by 184 governments worldwide to fight sexual exploitation , forced labor and moder-day slavery . The annual report , considered one of the most comprehensive analyses of worldwide human trafficking , ranks countries in three `` tiers . '' Mexico was put in the middle tier . Notably , the reported cited the municipality of Tenancingo as a major source for Mexican sex trafficking victims exploited within Mexico and in the United States . Women , children , indigenous people and undocumented migrants are especially vulnerable , the report read . While noting some of the recent strides made by the Mexican government in countering trafficking , particularly at the federal level , the study also cited reports that some local law enforcement officials tolerate and are sometimes complicit in the illegal trade . `` Given the magnitude of Mexico 's trafficking problem ... the number of human trafficking investigations , prosecutions , convictions , and sentences remained low , and government funding for victim services remained inadequate , '' it read . The State Department says 27 million people are victims of human trafficking worldwide , and approximately 100,000 of those victims are in the United States .
The investigation started with with a tip from ICE , authorities said . Investigators traced the victims to the southern state of Tlaxcala . They each will serve a total of 16 consecutive years in prison . Mexico , like many countries , struggles to prosecute and punish trafficking offenders .