Jeffrey Epstein's 2011 police mug shot.

U.S. District Judge Kenneth A. Marra of the Southern District of Florida ruled Thursday that prosecutors broke federal law in their handling of a case against Florida billionaire Jeffrey Epstein, who ran a global child sex ring between 1999 and 2007.

According to Marra's ruling, former Miami U.S. Attorney Alexander Acosta was wrong to set up a clandestine nonprosecution agreement with Epstein in 2008 that shielded him and his accomplices from federal prosecution.

Epstein pleaded guilty to two prostitution charges and served 13 months in Palm Beach County jail, but could have faced life in prison with a federal sex trafficking conviction. His alleged accomplices were never charged.

Read the ruling:

Marra found that because Acosta — now U.S. Labor Secretary — didn't tell victims about the deal, he violated their rights under the Crime Victims' Rights Act. The government argued that the law only required prosecutors to answer victims' questions, not to update them on every case development, but the court disagreed.

According to the ruling, while Acosta was working on the deal he sent letters to victims, urging them to be patient.

“Particularly problematic was the government's decision to conceal the existence of the NPA and mislead the victims to believe that federal prosecution was still a possibility,” Marra wrote. “When the government gives information to victims, it cannot be misleading.”

A federal investigation into sex abuse claims against Epstein had uncovered more than 30 teenage victims, including petitioners Jane Doe 1 and Jane Doe 2.

Epstein has also faced and settled various civil lawsuits over the international sex ring, involving claims he and his co-conspirators recruited underage girls and brought them to his Palm Beach mansion, where he forced them to perform sexual acts.

National women's advocacy group UltraViolet commended the ruling in a statement Friday, urging Congress to impeach Acosta.

“Under Acosta's leadership, a sexual predator and his accomplices walked away with a meager slap on the wrist,” the group's co-founder Shaunna Thomas said. “Epstein's nonprosecution agreement made the full scope of his crimes, and the identities of anyone else involved, completely private from the public, including from survivors.”

The White House told reporters at a press conference Friday that it's looking into Acosta's actions.

Fort Lauderdale white-collar criminal lawyer Richard Serafini, who has practiced in state and federal courts for more than 20 years, and said a ruling like this is rare.

“I have never seen it before,” said Serafini, who's not involved in the litigation. “After reviewing the decision, it seems that the judge came to the correct determination.”

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Feds to Investigate Billionaire Epstein's Sex Plea Deal

Justice Department Watchdog Looking Into Jeffrey Epstein Plea Deal