Up next, a late night walk in an upscale neighborhood results in murder.

The victim suffered a horrible agonizing painful death.

Surprise evidence sends investigators

in an unexpected direction.

Murder has no boundaries. We're going wherever we got to go.

After weeks of investigation, the case comes down to a single phone number.

The bottom line to this investigation is forensics. The cell phone

phone forensics actually brought the whole focus 180 degrees. The forensics is the

forensics is the glue that sticks it all together. After meeting online and living for a while in Europe, Fred and Sherry Engel married and moved his

consulting business to Myrtle Beach, South Carolina in 2006. The couple,

both in their early 50s, lived in a complex called Carolina Forest.

Carolina Forest was really a plan unit development, but it stretches into what was just

a bear track, wildlife track for many, many acres.

Tom and Karen Rickerson were the Engle's next-door neighbors.

We knew her first because she lived in Myrtle Beach

before Fred was able with this job to move there. They were very quiet, you know, like, you know, to themselves, very nice people.

Shortly before midnight on April 21st, 2008, Cherry woke up and couldn't find Fred.

He wasn't in the house, but his car was still in the garage.

She had worked herself up into a panic.

She knocked on her next-re-haber's door and very plainly said them,

but in a panic way, you know, I can't find Fred.

I don't know where Fred is.

...