The man who shot to Internet fame several years ago after appearing on TODAY to discuss a condition that permanently turned his skin a deep blue has died.

Paul Karason was 62 when he passed away Monday in a Washington hospital, where he was admitted last week after suffering a heart attack. He also had pneumonia and later suffered a severe stroke, his estranged wife, Jo Anna Karason, said Tuesday.

A cause of death was not immediately known, but Paul Karason had suffered heart problems for years, she said.

Karason started turning blue about 15 years ago after he began using a special silver-based preparation to treat a skin condition. He also had been drinking colloidal silver, a product consisting of silver particles suspended in liquid.

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In 2008, Karason emerged from his reclusive life to appear on TODAY to discuss his condition, known as argyria, which is caused by the use of dietary supplements. He appeared again on the show a year later.

Karason’s widow said some people had called her husband “Papa Smurf” because of his skin color and his white mane of hair and matching full beard.

“That was a nickname he didn’t appreciate, depending on who said it,” she said. “If it was a kid who ran up to him saying ‘Papa Smurf,’ it would put a smile on his face. But if it was an adult, well ….”

Karason began using a silver preparation to treat a bad case of dermatitis that had broken out on his face. He took the silver in colloidal form that he produced himself, using electrolysis.

Silver has antibacterial properties and has been used to fight infection for thousands of years. But it went out of use when the far more effective penicillin was developed in the 1930s.

It continued to be used in some over-the-counter medicines until 1999, when the FDA banned it because it causes argyria, which is a result of the silver reacting with light the same way it does in photography. The silver collects in the skin and other organs and does not dissipate.

Although Karason suffered from argyria, he had a long history of other health problems, mainly related to his heart. He was a heavy smoker, despite undergoing triple bypass surgery about five years ago, his widow said.

“He has been too ill to work for a while,” she said, saying Karason spent his last few years reading historical books and watching the History Channel.

“He didn’t like to go out in public much -- only when he thought he needed to, like to go to the bank or to pick up tobacco,” she said.