Up next, an insurance agent's murder stunned suburban St. Louis.

It was a broad daylight execution. It was shocking. This was a very brazen crime. Years pass. No one's arrested.

Until a suspect is identified by new technology.

It's a real game change.

And a killer soon learns you can't hide what you can't see.

This trial, I guarantee you he got an education. Nesled along the West bank of the Missouri River.

The St Louis suburb of St Charles looms large in U.S. history.

It marks the spot where in 1804 Lewis and Clark began their epic journey into the still uncharted American interior.

I was a stop for Lewis and Clark, so they're very proud of that.

There's a statue of Lewis and Clark down by the riverfront.

On the morning of June 8th, 2007, the peacefulness of this Midwestern community was shattered

when a postal worker doing her normal rounds made a

gruesome discovery. She found insurance agent Bob Edman bloody and

possibly dead in his office.

She saw the body and then ran out screaming as I think any of us would.

Police arrived to find Bob Edman dead at the scene. He'd been shot, execution style.

He was shot once in the face and in the neck.

The last shot, the shooter was standing over him,

looking down at him and fired one shot,

and went through and through his head

and buried itself in the floor.

This was cold-blooded murder,

...