But what led to his resignation?

Multi-millionaire hedge fund manager Jeffrey Epstein was indicted in New York on Monday on charges related to a sex trafficking ring he reportedly operated in New York and Florida in the early 2000s.

The charges against him aren’t entirely new, though. As far back as 2008 Epstein was the subject of an investigation involving the alleged molestation of at least 40 teenage girls. Epstein reached a secret plea deal at the time—with none other than Acosta, who was then serving as a federal prosecutor in South Florida. 

Epstein avoided federal charges that could have led to a life sentence. Instead, he served just 13 months in a work-release program that allowed him to leave 12 hours a day, six days a week, following lesser state charges.

In February, a federal judge ruled that Epstein’s deal violated the Crime Victims’ Rights Act, as it was struck without consulting with or informing Epstein’s victims. In other words, the people Epstein reportedly molested were kept in the dark and had no say in the deal. The agreement was only made public in 2015, when it was unsealed in a lawsuit.

With Monday’s indictment, Acosta has come under renewed scrutiny for the deal he brokered with Epstein 11 years ago. Acosta defended his decision earlier this week, claiming that he got the best deal he could at the time.

Speaking to reporters at the Labor Department, Acosta claimed that “facts are important and facts are being overlooked.” Arguing that such cases are “complex,” he said that state prosecutors had planned to go after Epstein on lesser charges and that it was only due to his office’s intervention that Epstein served time and was forced to register as a sex offender. “We believe we proceeded appropriately,” he said.

He further wrote on his official Twitter account on Tuesday that “new evidence and additional testimony” have now enabled “an important opportunity to more fully bring him to justice,” adding that he is “pleased that NY prosecutors are moving forward with a case based on new evidence.” 

Acosta told reporters Friday that he didn’t want involvement in Epstein’s case to distract from the work of the Labor Department. “It would be selfish for me to stay in this position and continue talking about a case that’s 12 years old rather than about the amazing economy we have right now,” he said. “I thought the right thing was to step aside.” Acosta reportedly plans to officially step down a week from today.

More must-read stories from Fortune:

—What to expect from the second Democratic debate

—Who wins and loses as White House withdraws drug rebate plan

—A new holding center for migrant children is open in Texas

—Fed Chairman Powell: If Trump asks me to leave, I won’t

—Tom Steyer mastered markets and now he wants to topple Trump

Get up to speed on your morning commute with Fortune’s CEO Daily newsletter.