(PHOENIX) — An Arizona millionaire who died minutes after he was convicted of arson appeared to have put something in his mouth while in the court room, sparking an investigation into whether the convicted arsonist had poisoned himself.

Michael Marin, 53, was convicted on Thursday of purposefully burning down his $2.55 million mansion in the tony Biltmore Estates neighborhood of Phoenix after he was unable to keep up with mortgage payments and a plan to raffle his house through a charity fundraiser failed. He faced up to 16 years in prison.

After the guilty verdict on one count of arson was read, a seemingly distraught Marin buried his face into his hands and appeared to place something in his mouth.

His face began to turn red. Minutes later, he took a sip of a liquid from a plastic sports bottle, turned to get a tissue, experienced convulsions and collapsed.

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He was pronounced dead at the hospital, said Jeff Sprong, spokesperson for the Maricopa County Sheriff’s Office, which is investigating the death.

“As you watch the video it does look like he is putting something into his mouth. Unfortunately we didn’t find any evidence he left behind,” Sprong said. “We are steering toward the fact he did ingest something. However, we’re going to have to wait for toxicology results in two to three weeks.”

Marin, who amassed his fortune working in finance and as a Yale-educated lawyer, set fire to his 6,600 square foot mansion on July 5, 2009 after he was unable to make a $2.3 million payment on his balloon mortgage the following month.

The 53-year-old had a taste for living large and was known for his eclectic interests. He was a self-published author. He owned and piloted a Cessna 310, had scaled Mt. Everest, served as a Mormon missionary and later as an executive in Japan, and was a diehard fanatic of the Burning Man festival.

But on Thursday, it became clear Michael Marin’s once-robust social life would be replaced with the prospect of spending up to 16 years in prison.

“We the jury, duly impaneled and sworn in the above entitled action upon our oath, do find the defendant Michael James Marin guilty of arson of an occupied structure,” said a foreman.

Moments later, Marin discreetly popped something into his mouth and died.

Copyright 2012 ABC News Radio