BOSTON -- A co-founder of EMC Corp. and former U.S. ambassador to Ireland who was battling Stage IV lung cancer committed suicide in his Boston home Friday, a law enforcement source told NewsCenter 5.

Richard Egan, 73, was inside his Four Seasons condo on Boylston Street when he killed himself in a closet. His wife and visiting nurse were in the home at the time and heard the gunshot.

"Ambassador Richard Egan died today at his home in Boston after a long illness," the family said in a statement.

The self-made billionaire, who raised seed money for his business by selling office furniture, was a key fundraiser for the Republican party and former President George W. Bush, becoming a Pioneer fundraiser for the president in 2000.

He stepped down as EMC chairman in January 2001, about three months before Bush nominated him to be the U.S. ambassador to Ireland.

The family said Egan was diagnosed with lung cancer in May and also suffered from emphysema, diabetes and high blood pressure.

"This is a great loss for our family and we are terribly saddened," the family said.

Egan leaves behind a wife and five children.

The family did not announce funeral plans.