Twenty years ago, Andrew Cunanan went on a cross-country crime spree that, when it ended, left five men dead in its wake. The final victim was world-renowned fashion designer, Gianni Versace. Ahead of Dateline NBC's investigation into the case, airing Friday at 9/8c, correspondent Keith Morrison reflects on the story that captivated the nation.

I think you wouldn’t quite believe it if I made it up - like a work of fiction - the place where the story hit its awful climax.

But it’s real enough.

The steps leading from the street up to that amazing old rebuilt mansion are carved in off-white coral, the wrought iron gates (rusting a little here and there) were, and are still, branded with the sign of Medusa.

But it’s a hotel now. Very exclusive. Guards at the gates gently - firmly - shooing tourists away.

Italian fashion designer Gianni Versace Sygma via Getty Images

Management very kindly let me have a look around (though of course I’d already heard all about the place from the one and only Antonio. Who you’ll meet. Lovely man).

I found myself imagining a Russian oligarch or two might be in there somewhere, their super-cars in a valet-tended garage impatiently awaiting the Miami Beach dark. I went into the marbled courtyard, ducked through an impeccably designed archway and looked out at the pool courtyard -- where very live decorative bodies were draped around the water’s edges in their gold-rimmed barely-there bathing suits.

Back inside, I bent down and admired - in close up - the tiles and marble pieces he had worked until they were just exactly the way he wanted them. His partner Antonio told us the story. How he’d tell the workers, ”Please, sand them down, those stones are too shiny.” And then… “Too much sanding, they’ve lost their color now, so polish them.” Not too slick, not too dull, each stone selected by the master, each yard of fabric for the walls, each rug, chair, bed post, corbel, door knob. Every over-the-top square inch of the place.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Watch 'The Death of Gianni Versace: A Dateline Investigation' Friday at 9/8c on NBC

Though I never met him, never knew him, I have met him through his friends, like Antonio, and I can feel his absence here in this unique place he created: Casa Casuarina.

The ‘master’ (and master of style he was) of that villa in Miami Beach - and of a world-wide revolution in fashion - was, of course, Gianni Versace, the final victim of a troubled young man named Andrew Cunanan, whose killing spree is the subject of our story.

Andrew Cunanan

What Cunanan did was: bludgeon to death a close friend, shoot a former lover in the head, torture and viciously stab to death a pillar of Chicago society, shoot - merely for the sake of a getaway car - a kindly cemetery caretaker in New Jersey, and blow away - execution style - an icon of modern fashion design.

But why? Why did he do it, why did it happen, how did it happen, why wasn’t he stopped?

I’ll tell you quite frankly, re-examining the events of the Andrew Cunanan murder spree sucked me in deep. Sorting it out could drive a person crazy. Fortunately, I was able to work through it with a detective novel’s ration of colleagues every bit as determined to know… well, you’ll see.

But before we found answers, before we dove head first into the puzzling story of Andrew Cunanan’s crimes, my enduring memory had been of a stake out.

A strange, tense and fascinating day.

It was the summer of 1997. Hundreds of police officers, at least that many reporters, had been stalking the streets and alleys of Miami Beach… looking, looking… for the most famous fugitive in America, Andrew Cunanan. We knew what he looked like; we had his picture.

But day after day, the search came up empty.

Keith Morrison covering the case in 1997. Dateline NBC

And then the word: someone - Cunanan maybe - had fired a shot from a houseboat anchored on the waterway. (The houseboat was owned by a man who made porno films, but who knew or cared just then).

I knew enough to chase after a Dateline producer who knew just about every inch of Miami, and he led me into an elegantly expensive backyard and to a low wall a few feet above sea level, from which perch the two of us stared stupidly across the water toward that blue lump of a houseboat.

50 or 70 yards away. Or so. And there we witnessed the end of one of the most puzzling episodes of American crime.

Now, 20 years later, the story is as bizarre as ever.

Maybe stranger still, because now we know more. A lot more.

So this time, as you watch our story, you just might sniff the answer to that vexing question: why?

The Death of Gianni Versace: A Dateline Investigation airs Friday at 9/8c on NBC.