Thomas H. Lee, known as one of the pioneers in the private equity business, was found dead in an apparent suicide at his office in Manhattan, New York.

The 78-year-old billionaire financier and investor was pronounced dead after first responders found him with a self-inflicted gunshot wound at around 11:10 a.m. Thursday, according to the New York Post.

"The family is extremely saddened by Tom's death. While the world knew him as one of the pioneers in the private equity business and a successful businessman, we knew him as a devoted husband, father, grandfather, sibling, friend and philanthropist who always put others' needs before his own," family friend and spokesperson Michael Sitrick said in a statement.

Lee, a Harvard graduate, was listed by Forbes as the 1,507th-wealthiest person in the world with an estimated net worth of $2 billion.

He is known as one of the first financiers to enter the leveraged buyout business, which is the buying of a company with money borrowed against the acquired business.

Lee founded Thomas H. Lee Partners in 1974 and focused on medium-sized companies with growth potential. The savvy investor's early gains include the purchasing of Ohio-based Sterling Jewelers for $28 million (90% of which he borrowed) in 1985 and then selling the company for $210 million in 1987.

One of Lee's best business moves is his 1992 purchase of the iced tea company Snapple, which saw a surge in sales under Lee's control. He sold Snapple in 1994 for $1.7 billion at a return of 32 times equity.

The Boston native's list of investments over the years includes Summit Behavioral Healthcare, Prelude Fertility, K-Mac Holdings and others.

Lee left Thomas H. Lee Partners and started Lee Equity Partners in 2006. He served as the chairman of Lee Equity Partners until his recent death.

He "was a pioneer and lion of the private equity and leveraged buyout industries, with the purchase and subsequent sale of Snapple Beverages and Warner Music among his many successful transactions," his family wrote in a statement, as quoted by Insider.

"Over the past 46 years, Mr. Lee has been responsible for investing over $15 billion of capital in hundreds of transactions," the family added.

If you have thoughts of suicide, confidential help is available for free at the National Suicide Prevention Lifeline. Call 1-800-273-8255. The line is available 24 hours a day.

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