Lottery winner at center of murder mystery

(CBS News) For six months, the grave of a million-dollar lottery winner who died suddenly last summer has been undisturbed at Chicago's Rosehill Cemetery. But that may soon change.

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Urooj Khan, the 46-year-old owner of a local dry cleaning business, hit the jackpot last June, opting to take out a lump sum which amounted to $425,000 after taxes.

He received the big check on July 19 -- and then died the next day. But the check was cashed on August 15. When a winner dies, lottery officials say it's usual that the money goes to his family.

Cook County medical examiner Stephen Cina said the cause of death was listed as a hardening of the arteries, indicating a heart attack or stroke.

"The initial investigation didn't suggest anything suspicious about his death," Cina said. "No flags."

But then, a relative of the dead man placed a call to authorities and Cina's office was asked to look a little deeper into the case.

When they took another look at their toxicology analysis, they found lethal levels of the poison cyanide in Khan's blood.

"Even routine toxicological testing and even some more advanced toxicological testing is not going to detect cyanide so you really have to be looking specifically for cyanide," said Dr. Michael Levine, an expert in emergency medicine and toxicology at USC.

And that turned the case into a homicide investigation, with the obvious question being whether someone killed Khan for his money.

Cina said it's now highly likely that Khan's body will be exhumed from the cemetery for further examination, to see if the victim might have something to say -- from the grave.

To watch Dean Reynolds' full report, click on the video player above.