01/08/2013 at 03:00 PM EST
Urooj Khan won a million dollar lottery, but he lost his life the day after collecting his winnings. Now, the authorities suspect that the Chicago man was the victim of foul play.
Pathologists initially believed Khan died of natural causes, but have since changed their minds after a relative asked them to re-examine his death and they detected lethal amounts of cyanide in his blood.
"We are investigating the incident as a murder and are working closely with the medical examiner," Chicago Police spokeswoman Melissa Stratton tells PEOPLE.
Khan, a 46-year-old hardworking entrepreneur from India, bought the two lottery scratch-off tickets at a convenience store near his home last June.
Moments after scratching off the second ticket, he reportedly jumped into the air and screamed, "I hit a million!" then handed the clerk a hundred-dollar bill out of gratitude.
On July 19, Khan cashed in his ticket and received a check (minus taxes) for $425,000, some of which he planned on donating to a local children's hospital.
The next day he was back at work at his string of dry cleaning businesses. But that evening, shortly after going to bed, he awoke shrieking in agony.
Shabana Ansari, 32, his wife of 12 years, telephoned paramedics and he was rushed to nearby St. Francis Hospital where doctors pronounced him dead several hours later.
Khan's blood sample showed no signs of carbon monoxide, opiates or alcohol. And because there were no visible signs of trauma to his body and no evidence of foul play, pathologists didn't believe an autopsy needed to be performed.
His death was attributed to hardening of the arteries and Khan was eventually buried at a local cemetery.
But before a week had passed, an unidentified relative telephoned the Cook County Medical Examiner's office, saying that he suspected foul play. A morgue worker took another look at Khan's blood sample and this time discovered lethal levels of cyanide.
"If a family member has a concern that seems valid, we take those seriously," Cook County Medical Examiner Stephen Cina tells the Chicago Tribune
. "We can't [ordinarily] look for every toxin under the sun like a CSI episode."
Homicide detectives are currently piecing together Khan's final days and deciding whether or not to exhume his body.