Jeffrey Epstein, a U.S. hedge fund billionaire with links to top politicians and celebrities, was charged Monday with running a sex trafficking ring that allegedly exploited dozens of underage girls.

In an indictment, Geoffrey Berman, a federal prosecutor in New York, accused Epstein of allegedly paying the girls hundreds of dollars for nude or partially nude massages that "increasingly were sexual in nature" at his mansion on New York's Upper East Side and at his estate in Palm Beach, Florida.

The prosecutor said Epstein often paid some of the victims, some as young as 14, to recruit other underage girls that he then also abused from 2002 to 2005.

"The alleged behavior shocks the conscience," Berman said of Epstein, who was arrested over the weekend when he flew back to the U.S. from Paris on his private jet. The prosecutor said that after Epstein's arrest, investigators searched his New York home and found photos "of what appeared to be underage girls."

Despite the fact that the allegations against Epstein stem from incidents that occurred more than a decade ago, Berman said, "We want to make sure [the accusers] have their day in court by bringing these charges."

The 66-year-old Epstein faces two charges, conspiracy to commit sex trafficking and sex trafficking. If convicted, Epstein faces up to 45 years in prison, which Berman said, because of Epstein's age, amounts to a life sentence. In a court appearance, Epstein pleaded not guilty to the charges.

Epstein is a well-connected financier whose friends have included two U.S. presidents, Donald Trump and Bill Clinton, and Britain's Prince Andrew.

WATCH: Epstein trial

In 2002, years before he entered politics, then real estate magnate Trump told an interviewer, "I've known Jeff for 15 years. Terrific guy. He's a lot of fun to be with. It is even said that he likes beautiful women as much as I do, and many of them are on the younger side."

Clinton often flew on Epstein's plane to the Little Saint James island owned by Epstein in the U.S. Virgin Islands. No one has alleged that either Trump or Clinton engaged in underage sex activities, although Andrew in 2011 was forced to quit his role as a British trade representative after a report surfaced that Epstein had arranged for Andrew to meet a 17-year-old girl.

Previous allegations

Epstein dodged significant jail time in Florida more than a decade ago when allegations against him of child sex trafficking first surfaced.

In that case, a federal investigation was halted when Epstein pleaded guilty to Florida state charges of a soliciting and procuring a person under 18 for prostitution. He ultimately served 13 months, but was allowed to spend half of most days at his Palm Beach office on a work-release program, a disposition of the case that the Miami Herald newspaper called the "deal of a lifetime."

Epstein's defense lawyers negotiated his plea deal with then U.S. Attorney Alexander Acosta, appointed by Trump in 2017 as labor secretary in his Cabinet.

Acosta has defended the resolution of the case, in part because it required Epstein to register as a sex offender.

But this year, a judge reviewing the outcome of the case in Florida ruled that Acosta and his fellow prosecutors violated the law by not informing the victims in the case that they were resolving the case with the state charges as the federal investigation ended. The Department of Justice, which oversees federal prosecutors, has opened an investigation into whether the lawyers committed "professional misconduct" in the way they resolved the case.

On Monday, Berman, the federal prosecutor in New York, said he was not a signatory to the Florida agreement and that there was no legal impediment to bringing the new charges.