Jeffrey Epstein, the financier charged with the sex trafficking of minors, was the sole director for the private-equity giant Leon Black's family foundation for more than a decade, tax filings seen by Business Insider show. Epstein stayed on even after pleading guilty to soliciting prostitution.

Black cofounded the $247 billion Apollo Global Management. He and his wife started a foundation in 1998 that donates to groups including a charter-school network and religious organizations.

The longtime philanthropic adviser Doug White told Business Insider it's "shocking" that Epstein, a registered sex offender, continued as the foundation's director even while he was in jail.

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Little is known about ties that Jeffrey Epstein, the financier charged Monday with sex trafficking and conspiracy, has had with the finance world since founding an investment firm in 1981 that has just one known client. But through reviewing years of tax documents, Business Insider uncovered a connection between Epstein and the private-equity billionaire Leon Black.

More business connections could soon come to light. Thousands of new documents are set to be unsealed in the case against Epstein, and a top lawyer representing two of Epstein's accusers told Business Insider that he was looking into Epstein's broader circle.

Black cofounded Apollo Global Management, the New York-based private-equity firm that manages about $250 billion on behalf of groups including public pension funds, endowments, and foundations. The CEO and his wife, Debra, a philanthropist and Broadway producer, created a family foundation in 1998. Epstein served as the director of the Debra and Leon Black Family Foundation from at least 2001 through 2012, tax documents searchable on ProPublica's database show — including for years after he pleaded guilty to prostitution charges in 2008 and registered as a sex offender.

Epstein is the only other person, besides Black and his wife, listed as an officer, director, trustee, or foundation manager during that time period. It's unclear what Epstein's role at the foundation was.

Multiple requests to reach the Blacks through Leon Black's outside advisers, as well as a call placed with the phone number listed for the family foundation, fielded no responses.

David Boies, the chairman of the law firm Boies, Schiller & Flexner who is an attorney for two of Epstein's accusers, told Business Insider that Epstein's business connections would be subject to more scrutiny. Les Wexner, the founder of the clothing brand The Limited who is a highflier in the fashion industry, has been, to date, the only publicly identified client of Epstein's investment firm.

"Exactly who he dealt with in his business ventures and the like is not something that we have insight into, in part because when I deposed him, he took the Fifth Amendment," said Boies, who questioned Epstein for 40 minutes last year in a deposition in which Epstein declined to answer any of Boies' questions. Boies does not have any active civil cases against Epstein.

There's no evidence that either the Debra and Leon Black Family Foundation or the Blacks are linked to any wrongdoing. Under Epstein's tenure, the foundation's beneficiaries included a variety of nonprofits, including many focused on children in New York, such as the charter-school network Harlem Village Academies, the Trinity School, and Prep for Prep, a leadership program for minority students.

At least one CEO of the nonprofits that received funding from the foundation said he was unaware of Epstein's involvement.

For the longtime philanthropic adviser Doug White, Epstein's role as director at the foundation — which based on the tax documents continued while he served time in a Florida jail after pleading guilty to two charges of soliciting a minor for prostitution — raises red flags.

"A foundation, specifically a charity foundation, should not have as one of its directors someone who has pleaded guilty to a sex crime and is officially labeled a sex offender," White, who overlapped at Dartmouth College with Leon Black, told Business Insider. "Leon in particular should be sensitive to that kind of thing. But he stayed on the board for another four years, which is the most eye-raising thing."

A foundation director's role includes overseeing the direction of its charitable activities, White said. A director would also oversee staff, though the Black foundation's filings do not indicate any employees. For a small foundation like the Blacks', the president — in this case, Leon Black — may have been deciding where funding went, and Epstein could have been acting as a "rubber stamp," White said. He said the typical family foundation had three to four meetings a year, where executives read proposals and allocate funds to charities.

"From a governance perspective, it's shocking," White said. "After the guilty pleas, Leon Black had no reason to keep him on the board."

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New charges for Epstein

Epstein was arrested Saturday evening and charged with trafficking dozens of girls as young as 14 in the early 2000s, according to a federal indictment unsealed Monday. He appeared in court and pleaded not guilty to the charges. The news comes more than a decade after Epstein avoided federal charges in a plea deal that has long drawn scrutiny.

The new charges allege that Epstein systematically molested dozens of underage girls by paying them for "massages" that rapidly devolved into sexual abuse. The indictment says the abuse occurred in Epstein's homes in New York City's Upper East Side and in Palm Beach, Florida, between roughly 1999 and 2005.

Epstein has long faced allegations of sexual abuse, and he was investigated by the Palm Beach Police Department in 2005. But in 2007 he cut a secret nonprosecution agreement with Alex Acosta, then a US attorney but now President Donald Trump's secretary of labor.

The deal granted Epstein immunity from federal prosecution, and Epstein pleaded guilty only to two state charges: solicitation of prostitution and procurement of minors for prostitution. Epstein ultimately served a 13-month jail sentence, but because of a work arrangement he was allowed to leave jail six days a week to work out of his Palm Beach office, according to The New York Times.

On Wednesday, a New York federal appeals court ordered that up to 2,000 documents related to a previously settled Epstein case be unsealed in coming weeks, raising questions about who in Epstein's orbit might be implicated.

"There is an enormous amount of information there," said Boies, the lawyer for Epstein's accusers. "A lot of stuff is going to come out."

With additional reporting from Michelle Mark.