are being offered work in hotels or restaurants or in child care and are forced into prostitution with the threat or actual use of violence. Estimates of the number of victims vary from 1,000 to 7,000 on a yearly basis. Most police investigations on human trafficking concern legal sex businesses. All sectors of prostitution are well represented in these investigations, but window brothels in particular are overrepresented. At the end of 2008, a gang of six people was sentenced to prison terms of eight months to 7½ years in what prosecutors said was the worst case of human trafficking ever brought to trial in the Netherlands. The case involved more than 100 female victims, violently forced to work in prostitution. In December 2009, two Nigerian men were sentenced to 4 and 4½ years in prison for having smuggled 140 Nigerian women aged 16–23 into the Netherlands. The women were made to apply for asylum and then removed from asylum centers to work as prostitutes in surrounding countries. The men were said to have used "voodoo" curses on the women to prevent escape and enforce payment of debts. The United States Department of State Office to Monitor and Combat Trafficking in Persons ranks the Netherlands as a 'Tier 1' country. See also Prostitution in the Dutch Caribbean References Sources Kuisheid voor mannen, vrijheid voor vrouwen (1997), Petra de Vries (Chastity for men, freedom for women) Mobiliteit in de Nederlandse prostitutie 1998–1999 (Mobility in Dutch prostitution 1998–1999) Nghiệp đoàn mại dâm Amsterdam chống giảm giờ làm ăn, in Vietnamese (Amsterdam sex workers union against reduced business hours) Prostitutie naar een illegaal en onzichtbaar circuit? Een verkennend onderzoek naar enkele onbedoelde gevolgen van de opheffing van het bordeelverbod in Twente, by M.D.E. Averdijk 2002 (Is Prostitution an illegal and invisible circuit? An exploratory investigation of some unintended consequences of abolishing the ban on brothels in Twente) Migration and trafficking Human trafficking in the Netherlands Website of the Dutch Coordination Centre Human Trafficking (CoMensha) Dutch National Rapporteur Website of the Dutch National Rapporteur on Trafficking in Human Beings and Sexual Violence against Children Trafficking in Human Beings, First report of the Dutch National Rapporteur, Second report, Third report, and Fourth report Research based on case studies of victims of trafficking in human beings in 3 EU Member States, including the Netherlands. Dina Siegel: Human trafficking and legalized prostitution in the Netherlands. Temida March 2009