Here in Chicago and in cities throughout the nation, hospitals have been flooded by calls from people fighting by the Tylenol scare.

What started as a series of mysterious unrelated deaths 48 hours ago has resulted in the biggest drug warning in U.S. history.

The sixth person has died after taking a Tylenol capsule laced with cyanide.

Do not take any Tylenol until further notice.

In the fall of 1982, seven people in the Chicago area mysteriously died after taking the

over-the-counter pain medication Tylenol. Authorities raced to figure out what was going on and soon realized this wasn't a freak accident.

It was an attack, carefully plotted and executed.

Someone had replaced ordinary Tylenol with poisonous capsules, and it sent the whole world into a frenzy.

It made no sense at all.

It was such an arbitrary act of evil against humanity.

The case became known as the Tylenol murders.

And if you think you already know this story, believe me, it goes much, much deeper than the headlines.

I'm St. Clair.

Test, test.

Testing. This is Christy Katowski.

Christy and I are investigative reporters with the Chicago Tribune.

This story has hovered over both of our careers for decades, and it has remained unsolved.

Now, time is running out.

But Christy and I have uncovered new evidence, followed fresh leads, and have spoken to sources who have never gone on the record until now.

We'll take you inside the FBI's latest,

and what may be their last attempt at closing one of America's most haunting unsolved cases.

There were times when he would look at you, and he'd just smirk.

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