Police and prosecutors arrested four alleged pimps Monday morning as part of an ongoing investigation into a ring of human traffickers who preyed on abused and neglected children in foster care.

The men, police say, were part of an organized conspiracy to lure underage girls into prostitution. The four were charged with conspiracy, racketeering and unlawful sexual activity with a minor.

Using a teenage foster child as a recruiter, police say, the four men plied underage girls with cash, affection and gifts. Ultimately, the girls became prostitutes who earned the ring about $100 for every man with whom they had sex. The girls, in turn, were paid $30 or $40 of that original $100.

Beginning in January of 2011, members of the ring would call girls on cell phones supplied by the men and arrange for them to have sex at a building in Homestead that the ring used as a kind of brothel, records say.

Charged Monday were Eric George Earle, 29, called “E-Nasty,” Willie Calvin Bivens, 65, called “Tank,” Anturrell Nathaniel Dean, 30, and David Zarifi, 34. A fifth person — a 17-year-old foster child who is identified only by the initials S.S. — is listed in a 13-page sworn statement as a “recruiter” for the ring, though she is not charged with any crimes. As of late Monday, the four men remained in jail: Zarifi on $53,000 bail, Earle on $60,000 bail, Bivens on $35,505 bail, and Dean on $45,000.

The human trafficking investigation also involves a now-suspended child abuse investigator for the agency that oversees child welfare efforts in Florida. Jean LaCroix, a child protective investigator employed by the Department of Children & Families, was placed on paid administrative leave while police and prosecutors investigate allegations he repeatedly had sex with a teenaged foster child whose safety he was assigned to protect.

Sources have told The Miami Herald that LaCroix placed the girl at a group home for dependent children — and turn returned to the home repeatedly to pick the girl up for sexual favors. The girl, sources say, also was working for members of the ring who were arrested Monday.

LaCroix had spearheaded a 2006 child abuse investigation — prompted by a call from worried teachers and administrators — into the welfare of Nubia Barahona, a twin who was adopted from foster care and was killed in 2011, police say by her own adoptive parents, Carmen and Jorge Barahona. LaCroix was named in a lawsuit alleging DCF failed repeatedly to protect Nubia, and her brother, Victor, whom police say also endured years of torment.

LaCroix has not been charged with any crimes.

The investigation began in December 2011 when a foster child disclosed that she had been having consensual sex with a man.

The 17-year-old, identified as M.D., allowed police to search her cellphone. It contained images of the girl both naked and having sex with Zarifi, a sworn statement says. M.D., police say, suffers from cognitive impairments.

M.D. told police that, soon after she went sent to live in a state-operated group home in September 2011, she was recruited by a housemate, S.S., who told her “she could make money by having sex with men,” a warrant states. At first, she was introduced to a man she then knew only as “E-Nasty.” But Earle introduced her to Zarifi, whom she told police was “nice to her.” M.D. liked Zarifi so much that she had sex with him for free after being paid four times.