(NBC NEWS) – Tonight on “Dateline,” the death of beloved Vietnam War veteran Bob McClancy is believed to be a suicide until a dark conspiracy is uncovered.

Here is a preview of Keith Morrison’s report:

This place, where the story begins, seems created not for lies, but for love.

The tranquil waters and soft sunsets of Bradenton, Florida.

And though the local sheriff’s office may seem an unlikely place to find love, here’s where it struck a county detective named Bob McClancy.

OFF CAM:  GOT ANYTHING TO SAY, BOBBY?

BOB MCCLANCY: I GOT A LOT TO SAY. HOW MANY HOURS DO WE HAVE LEFT ON THE TAPE?

A funny man.

BOB MCCLANCY: WELCOME TO PASQUALE’S KITCHEN.

And very kind, said his nieces.  Not just to people. 

KIM ILLUM: WE’D BE SO EXCITED TO GO OVER THERE TO SEE, LIKE, WHAT NEW ANIMAL HE GOT OR, YOU KNOW, LIKE, HE WOULD BE LIKE, “OH, I GOT A NEW BIRD, COME OVER AND SEE IT.”

BOB MCCLANCY: GIMME KISS.

KIM ILLUM: HE HAD GOT US– LITTLE TURTLES AS– KIDS.

KEITH MORRISON: HE WAS A REAL ANIMAL GUY, WASN’T HE?

KIM ILLUM: HE WAS, YES.

Loved his nieces, too.

KRISTIN CONKLIN: HE USED TO TAKE US OUT ON THE BOAT. HE JUST ALWAYS TOOK CARE OF US.

Just like he took care of his sister Kathy when they were kids.  

KATHY INZERILLO: IT WAS ALWAYS LIKE THE TWO OF US DOING EVERYTHING, UH-HUH.

KRISTIN CONKLIN: CAUSING HAVOC.

As a sheriff’s deputy, said his sister Kathy, he once faced down a violent gang.

KATHY INZERILLO: THEY HAD KNOCKED HIM TO THE GROUND AND TOOK HIS GUN AND EVERYTHING AND BEAT HIM UP, AS A MATTER OF FACT, I BELIEVE THAT THEY FIRED A SHOT, BUT IT MISSED.

KEITH MORRISON: SO HE BARELY MADE IT THROUGH THAT ONE.

KATHY INZERILLO: YEAH.

His marriage couldn’t take it. Bob McClancy sought love elsewhere.

And then a southern belle at the sheriff’s department – an aloof secretary known as the office whizz – caught his eye.

Watch Friday’s “Dateline: Secrets in the Smokey Mountains” tonight at 9 p.m. on NBC4.