A South Florida man is facing federal charges after authorities say he ran an elaborate sex trafficking ring for years, preying on vulnerable young girls and women and even going so far as to set up a phony non-profit organization that claimed to help trafficking victims.

William Foster, 48, was arrested Thursday on multiple charges including sex trafficking of a minor, conspiracy to sex traffic a minor, and transportation with intent to engage in prostitution, according to a criminal complaint.

The complaint said the FBI began an investigation into Foster in February 2017 after three alleged victims came forward and claimed they were recruited into Foster's organization, abused and sex trafficked from homes in Delray Beach.

Investigators discovered Foster had been running a human trafficking ring from Palm Beach to Miami-Dade for 15 years, with between five and fifteen females living with and working for him as prostitutes at any given time, the complaint said.

The victims told investigators they had engaged in sex with Foster beginning when they were minors. One victim said she was recruited out of high school while in foster care, and said Foster told her the best places to recruit minors and young women was from group homes, shelters, exotic dance venues because the "young women at those locations were vulnerable and in need of help," the complaint said.

Foster "used displays of a fun and wealthy lifestyle as a way to recruit new females," letting some of the girls and women drive high-end cars and wear designer clothes, shoes and handbags, the complaint said. Foster would also place the females on a "lemon diet" and funded cosmetic surgery for some, including breast augmentation, buttock injections, rhinoplasties and rib removals, the complaint said.

The females said Foster taught them how to target wealthy men as prostitution clients, and the women would attend yacht parties and dinners for wealthy clients, the complaint said. The females would travel out of state, to places like New York and Nevada, for prostitution work, and when Hurricane Dorian was approaching in September he flew some girls to Detroit so they could keep working for him, the complaint said.

Starting in 2014, Foster served as the president of a not-for-profit corporation called Foster's Care, the complaint said. State records showed the purpose of the non-profit was to provide "social services, counseling, shelter & education, to the youth and young adults in the tricounty area," the complaint said.

Foster's Care also had a website that claimed to provide free services including housing, therapy, medical treatment and job training to victims of sex trafficking, the complaint said. The website also discussed the C.A.R.E. program, standing for Changing Accepted Realities Effectively, a "comprehensive restoration program for victims of human sex trafficking," the complaint said.

The complaint said Foster or one of his associate would keep the money the females made and told them their earnings were being invested on their behalf, but they were never given any of the money.

Foster "used deceit, manipulation and fear of physical harm to cajole women and minor females to engage in commercial sex for the benefit of Foster's organization," the complaint said.

"These girls who end up in foster care already come hurt and they're full of pain. Their biological home situation is not the best and for somebody to have created a website and to prey on them, is just despicable," said Nelson Hincapie, with the Voices for Children Foundation in Miami. "Anytime anybody takes advantage of victims or young girls who end up in foster care is a terrible predator."

Foster remained behind bars Friday and was due in court next week for a bond hearing. Attorney information wasn't available.