Alex Navab, a former executive of KKR & Co. Inc. (NYSE: KKR), 53, died unexpectedly July 7 while on vacation with his family in Greece, according to Navab Capital Partners, a private equity firm he founded earlier this year. A cause of death was not provided.

Navab, who was once considered a potential candidate to lead KKR, left the firm in 2017 when other executives were promoted. In April 2019, Navab launched the eponymous firm, planning to back upper mid-cap to larger enterprises in North America. Navab had just completed hiring a stellar group of executives that he pulled from top firms, including KKR, the Carlyle Group (NASDAQ: CG) and Warburg Pincus. The firm was looking to raise $3 billion for its inaugural fund. The New York-based firm expected to invest in a wide range of industries including healthcare, technology, media, fintech, financial services and consumer. The firm also had a philanthropy component to it and had already established a foundation that would supply financial and human capital to philanthropic initiatives.

“All of us were committed to help make Alex Navab’s vision a reality, however we have determined it does not make sense to go forward without him at the helm,” the firm told Bloomberg News. “Navab Capital Partners will not pursue plans to raise a fund, and will wind down in an orderly fashion. We continue to grieve this terrible loss, and in our individual ways, we will cherish Alex’s memory and support his legacy of business and community leadership.”

Navab rose to prominence in the PE industry as the co-head and head of Americas Private Equity Business at KKR. Navab joined KKR in 1993 and held several leadership positions at the firm, including serving as a member of the management committee. Navab oversaw numerous leveraged buyouts at KKR, including Nielsen Co. and Yellow Pages. As head of North American buyouts, he helped the firm raise nearly $14 billion for its twelfth North American private equity fund.

“We are heartbroken,” said KKR founders Robert Kravis and George Roberts in a statement. “Alex was an outstanding investor, leader, mentor and a friend to many. His contributions in business and philanthropy over his lifetime will forever remain part of his remarkable legacy.”

Navab was born in Isfahan, Iran. At the age of 14, he and his family fled to Greece after the Iranian revolution in 1979. Following two years of dislocation, Navab and his family immigrated to the U.S. Navab graduated from Columbia University and worked at Goldman Sachs before attending Harvard Business School, from which he graduated in 1991. He worked at the investment bank James D. Wolfensohn Inc. before joining KKR.

Navab was an active philanthropist. He was a trustee at Columbia — to which he gave $6 million to fund internships for students — and a board member of New York-Presbyterian Hospital and the Robin Hood Foundation.

Navab is survived by his wife Mary Kathryn Navab (pictured), parents and three young children.