Urooj Khan, 46, won $1 million off a scratch lottery ticket he bought at a 7-11 in Chicago last June, but just one day after receiving his check, he died. Now, his death has been ruled a homicide, as toxicology reports showed deadly cyanide in his system. NBC's Andrea Canning reports.

A lottery winner was fatally poisoned with cyanide just as he was about to collect his payout on a $1 million instant lottery ticket, a Chicago medical examiner said Monday.

Urooj Khan died July 20, one day after the state issued a check to him for $425,000, which represented the after tax amount on the lump sum payout on his winning ticket. The check wasn’t cashed until Aug. 15, likely by a member of his estate.

After a limited exam, Cook County Medical Examiner Stephen Cina found no trauma or unusual substances in the 46-year-old's body, and the medical examiner's office declared that he died of natural causes.

Khan was buried at Rosehill Cemetery in Chicago, but within a week a concerned relative asked the medical examiner's office to take a closer look.

“They had concerns that it was deemed a natural cause of death and wanted us to look harder,” Cina told NBCChicago.com. “And we did.”

The medical examiner’s office determined from comprehensive toxicology reports that Khan had ingested a deadly amount of cyanide and his death has been reclassified as a homicide.

Police are considering exhuming his body as part of the investigation.

Lottery winner killed by cyanide was immigrant, family man

“It’s a very lethal drug,” Cina said of the lethal dosage of cyanide investigators found in Khan’s toxicology samples. “It’s a chemical poison. It basically asphyxiates you at the biochemical level, so a little goes a long way.”

Khan bought his winning ticket at a 7-Eleven near his home in West Rogers Park, a neighborhood on Chicago's North Side. A native of India, he came to Chicago in the late 1980s and began working at a dry cleaners. He grew his business to include three Chicago-area dry cleaners, and reportedly planned to invest his lottery winnings in his stores.

He also planned to give some of his winnings to St. Jude Children’s Research Hospital.

Khan described his gleeful reaction to winning in a June press release from the Illinois Lottery. “I scratched the ticket, then I kept on saying, ‘I hit a million!’ over and over again,” Khan said. “I jumped two feet in the air, then ran back into the store and tipped the clerk $100.”

Khan’s wife declined an interview with NBCChicago.com outside one of her deceased husband’s dry cleaners. Her husband was a “kind and good-hearted person,” she said.

“He was a family man who worked hard for his family,” friend Jimmy Goreel told NBCChicago.com. “I just can’t see it happening. If that’s true, it’s sad."

The Associated Press contributed to this report.

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