Thomas H. Lee, a billionaire private equity investor and part of the group that acquired Warner Music from Time Warner in 2004, died Thursday (Feb. 24) in New York at age 78, his family said in a statement.

A pioneer in the private equity world, Lee was the chairman of Lee Equity and formerly the chief executive of Thomas H. Lee Partners, the namesake firm he founded in 1974. Over nearly five decades in finance, Lee invested $15 billion in hundreds of companies and transactions, including the acquisition and sale of household brands like Snapple.

The Wall Street Journal, citing a New York Police Department source, said Lee was found dead in a bathroom at his Fifth Avenue office from what first responders believe to be a self-inflicted gunshot wound to the head. They were responding to an emergency call placed Thursday morning by Lee’s office assistant, the WSJ reported.

“The family is extremely saddened by Tom’s death,” Lee’s family said. “Our hearts are broken. We ask that our privacy be respected and that we be allowed to grieve.”

Lee’s Thomas H. Lee Partners, Bain Capital, Providence Equity Partners and Edgar Bronfman Jr. bought Warner Music from Time Warner Inc. for $2.6 billion in 2004. The group took the company public the following year, and Lee’s firm, Bain Capital Partners and Bronfman controlled 56% of Warner’s outstanding shares when it was sold to Len Blavatnik‘s Access Industries in 2011 in a deal valued at $3.3 billion.

Lee sat on WMG’s board as a director from 2004 to 2021, when he became a director emeritus.

“We are deeply saddened by the passing of our friend and colleague Tom Lee,” Warner Music Group CEO Robert Kyncl said in an emailed statement. “Tom made valuable contributions to WMG’s trajectory for almost two decades. Tom’s experience, wisdom, and enthusiastic support helped guide WMG through periods of major transformation, both within our company and in the music industry at large. Our condolences go out to his family and many friends.”

When Lee announced he would retire from the role of WMG board director in 2021, he described the company as having “undergone an extraordinary evolution,” and said he was gratified to have helped it transform and grow.

Lee was worth an estimated $2 billion, according to Forbes, and he was an active philanthropist involved in several New York City cultural institutions, including Lincoln Center for the Performing Arts and the Museum of Modern Art.