Michael Marin, 53, died Thursday soon after paramedics rushed him from the courtroom, The Arizona Republic reported.
A jury found Marin guilty Thursday of setting his mansion in the Biltmore Estates neighborhood in Phoenix on fire in 2009. A few minutes later, lawyers and the judge were discussing a hearing on aggravating factors when TV footage showed Marin putting something in his mouth and taking a drink from a bottle he pulled from his briefcase.
Marin collapsed 7 minutes later.
Marin could have been sentenced to almost 16 years in prison.
A lawyer with a degree from Yale, Marin made millions of dollars trading on Wall Street, the New York Daily News reported. He also spent lavishly, buying Picasso sketches and climbing Mount Everest.
When his mansion burned, he owed $17,500 a month on the mortgage and a balloon payment of $2.3 million was about to fall due. He said the fire was accidental and he escaped using a scuba mask and oxygen tank.
Fire investigators, however, said they found that trails of flammable trash had been laid down and the fire started in four places.