The Justice Department has opened an investigation into federal prosecutors' handling of a plea deal in which a wealthy, politically connected Florida financier avoided potentially severe penalties for sexually abusing teenage girls in favor of a relatively light state conviction.

The department's Office of Professional Responsibility wrote in a letter Wednesday to U.S. Sen. Ben Sasse, R-Nebraska, that it would examine whether professional misconduct occurred in the highly publicized case of Jeffrey Epstein. The letter cited a series of recent articles by the Miami Herald that focused new attention on how the deal came about.

Sasse, a member of the Senate Judiciary Committee who has twice asked the Justice Department to investigate the case, welcomed the news.

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"Jeffrey Epstein is a child rapist and there's not a single mom or dad in America who shouldn't be horrified by the fact that he received a pathetically soft sentence," Sasse said in an email. "The victims of Epstein's child sex trafficking ring deserve this investigation — and so do the American people and members of law enforcement who work to put these kinds of monsters behind bars."

Florida financier Jeffrey Epstein Florida Department of Law Enforcement via Reuters

Epstein, now 66, reached a nonprosecution deal in 2008 with then-Miami U.S. Attorney Alexander Acosta's office to secretly end a federal sex abuse investigation involving at least 40 teenage girls that could have landed him behind bars for life. He instead pleaded guilty to state charges, spent 13 months in jail, paid settlements to victims and is a registered sex offender.

Acosta, now President Donald Trump's labor secretary, has defended the deal as appropriate but has not commented since the recent round of stories. He was asked about the case during his Senate confirmation hearings for the Cabinet post.

"At the end of the day, based on the evidence, professionals within a prosecutor's office decided that a plea that guarantees someone goes to jail, that guarantees he register generally and guarantees other outcomes, is a good thing," he said.

The U.S. attorney's office in Miami had no immediate comment Wednesday on the new investigation. An attorney for Epstein did not immediately respond to a request for comment.

According to court papers, Epstein had a Palm Beach mansion where underage girls were brought for what they were sometimes told were massage sessions but often turned into sexual encounters. He allegedly had female fixers who would look for suitable girls, some local and others recruited from Eastern Europe and other parts of the world.

Before the scandal broke, Epstein was friends with Mr. Trump and had visited his Mar-a-Lago resort. Mr. Trump at the time told interviewers that Epstein was "a great guy." Records also show former President Bill Clinton flew on Epstein's jet more than two dozen times on various philanthropic trips.

Some of his accusers are pursuing a separate legal effort to nullify the plea agreement and, they hope, expose him to federal prosecution again. That lawsuit in West Palm Beach federal court contends their rights as victims were violated because they were not consulted or informed about the nonprosecution agreement before it was finalized.