Moments after attorney Michael Marin was pronounced guilty of arson in Maricopa County Superior Court on Thursday, the one-time high roller went into convulsions and collapsed.

By the time paramedics got him to the hospital, he was dead.

Investigators suspect he poisoned himself rather than face a possible 15 3/4 years in prison. Video of the sentencing shot by a television pool photographer appears to show Marin putting something in his mouth in the seconds after the verdict was read.

A Maricopa County Sheriff's Office spokesman confirmed that detectives are considering poison as the cause of death.

2009 Biltmore fire photos

Marin, 53, had fashioned a larger-than-life persona. Tall and distinguished, he had a law degree from Yale University and had scaled Mount Everest. He flew planes and wrote books. He owned a mansion full of fine art in the ritzy Biltmore Estates neighborhood of Phoenix. He had amassed a small fortune -- and lost it.

His mansion caught fire in July 2009. Marin said he barely escaped by climbing down a rope ladder from the second floor while wearing a scuba tank and diving mask to protect him from smoke inhalation.

But inside, arson investigators found boxes of flammable debris laid end-to-end through the house from the four ignition points, as if to feed the blaze. Marin was charged with arson of an occupied structure.

"Michael Marin couldn't pay his mortgage, so he burned down his house," Deputy Maricopa County Attorney Chris Rapp said in opening statements of the trial on May 21.

Rapp laid bare Marin's dire financial straits. In the year before the fire, his bank account shrank from $900,000 to just $50. He had a monthly mortgage of $17,250 on the mansion with a balloon payment of $2.3million coming due. In addition, Marin paid another $2,500 per month on a more modest home in Gilbert -- where Rapp said he actually lived -- and had an overdue tax bill of more than $34,000.

Marin tried to set up a raffle to pay off the loan, but it was deemed illegal by law enforcement and shut down. Then the house burned.

On Thursday, the jury reached a verdict, and Marin and his attorneys were summoned to the courtroom of Judge Bruce Cohen for a 12:30 p.m. hearing.

All eyes were on the court clerk as she read the verdict on a single count. Then the jury left the room so that Cohen and the attorneys could set the ground rules for the ensuing hearing about whether there were aggravating factors that could result in a harsher sentence for Marin.

What video later revealed is that seconds after the verdict was read, Marin rubbed his cupped hands across his face with an expression of dismay. His mouth seemed to open beneath the hands and it appeared as if he swallowed something. Then he took a sports-drink bottle from a briefcase and drank from it.

Seven minutes later, Marin coughed and reached for a tissue handed to him as he sat at the defense table. He buried his bright-red face in his hands and appeared to sob.

But the sobs turned into hoarse snores and whoops as hewent into convulsions. Marin dropped to his knees, and then fell face-first on the carpet as his attorneys tried to assist him. They pulled off his tie and opened his shirt, and when he began to vomit a clear liquid, they turned him on his side so he wouldn't choke. But he still had a pulse and was breathing.

When Phoenix Fire Department paramedics arrived, they immediately began chest compressions. Cohen cleared the courtroom.

When firefighters wheeled Marin out on a stretcher, his cheeks had gone gray and he had not regained consciousness.

The attorneys and the judge pondered what to do. Cohen released the jury for the day.

Then the word came: Marin was dead.

"I'm at a loss for words, honestly, at this point," Cohen said.

Phoenix Fire Captain Jeff Peabody told The Arizona Republic that Marin was pronounced dead at Banner Good Samaritan Medical Center.