(Arizona Republic) -- A former Wall Street trader whose dramatic death in a Phoenix courtroom was witnessed by millions on TV and the Internet, probably committed suicide with a homemade cyanide pill.

Marin collapsed moments after a jury found him guilty of burning down his Biltmore Estates mansion in 2009. Television video from Marin's court hearing appeared to show him putting something in his mouth immediately after the verdict was read. Seven minutes later, he went into convulsions and fell to the floor. Paramedics were unable to revive him.

Authorities had suspected that arson defendant Michael Marin committed suicide by ingesting poison after he collapsed in court on June 28, moments after a jury found him guilty of burning down his Biltmore Estates mansion in 2009. That theory was bolstered this week when Maricopa County investigators discovered a canister of cyanide in Marin's car.

Television video from Marin's court hearing appeared to show him put something in his mouth immediately after the verdict was read. Seven minutes later, he went into convulsions and fell to the floor. Paramedics were unable to revive him.

According to Sheriff Joe Arpaio, one of Marin's family members received a delayed e-mail from Marin the evening after his death stating that if things went bad for him in court he had prepared a last will and testament and that his car could be found parked in Mesa. Sheriff's investigators were informed of the e-mail by the family and obtained access to the car Monday night.

Arpaio said Tuesday that a silver canister labeled "sodium cyanide" was found in the car, and evidence indicated that it had been purchased by Marin over the Internet in 2011 from a California supplier called Chemical-Supermarket.com and was delivered to him by United Parcel Service.

The company was contacted by the Sheriff's Office and is cooperating with the investigation. Arpaio said investigators did not open the canister, described as the size of a coffee can, but said that it appeared to contain a light powder.

The can was turned over to the Maricopa County Medical Examiner's Office, where its contents will be compared with any substances found in Marin's body by toxicology testing.

Arpaio said that Marin's grown children are cooperating with authorities and that investigators have also spoken to Marin's girlfriend, Susie Spicer, who was with him in court when he died. None of them has spoken publicly about Marin's death.

"All indications point to suicide, but until the (medical examiner's) final report, the investigation remains open," Arpaio said.

Cyanide is used in mining to separate precious metals from ore, and it has uses in other industries as well, according to information on the Chemical- Supermarket.com website. It is not a controlled substance, but it is highly toxic and kills rapidly by directly poisoning cells and inhibiting the body's use of oxygen.

"Cyanide goes to the top of the list of things we would refer to as knock-down agents," said Dr. Anne-Michelle Ruha, a toxicologist at Banner Good Samaritan Medical Center in Phoenix.

From watching the video of Marin's collapse, Ruha speculated soon after the incident that cyanide was involved. Most other chemicals that kill quickly are gases, she said, but it takes only about 200 milligrams of cyanide for a fatal dose.

"We see a lot of suicides and suicide attempts," Ruha said, "but cyanide is rare."

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