Just weeks before testifying at a criminal trial, one of the key witnesses, a brilliant research scientist was murdered.

For 15 years, there were many suspicions, but little proof.

Ironically, advances in the very research the victim had been working on helped nail her killer.

When you ask friends and colleagues about Helena Greenwood, you hear words like brilliant, quiet, honest, and a hard worker.

Helena earned a Ph.D. in microbiology and was an executive in the biotech industry.

She not only was an excellent scientist,

but she had marketing skills, and those two things often are not concurrent. Helena was very forward-thinking, especially looking at technology, but she also knew the power that technology by itself doesn't market a product.

Basically, it's the human need.

If there's a human need, there's a product that's required.

Helena and her husband Roger, a landscape designer, lived in Atherton, a quiet suburb outside San Francisco.

Our story begins on a Saturday night in April of 1984 when Roger was out of town on a business trip.

In the middle of the night,

a man suddenly appeared in Helena's bedroom

and threatened to kill her.

Helena was sexually assaulted, then robbed,

before the assailant made his getaway.

Dr. Greenwood described her assailant as being fairly tall, slender, athletic,

with a complexion, perhaps of half-black or Hispanic person, an olive complexion.

She couldn't see his face because he had a hooded sweatshirt, pulled up so that only his eyes showed.

The assailant entered the home through a kitchen window.

But it was Helen's friend who found a key piece of evidence that police had overlooked.

Outside on the deck near the kitchen window was a teapot from Helena's kitchen.

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