(NBC News) — Friday on “Dateline,” when New Jersey mother Michelle Lodzinski reports that her five-year-old son Timmy vanished from a carnival, detectives embark on a decades-long investigation, until a family member identifies a key piece of evidence pointing to a potential suspect.

Here is a preview of Andrea Canning’s report:

It was a moment that devastated nearly everyone in this quiet corner of suburbia.

ANDREA CANNING: This is really a parent’s worst nightmare.

SIBILE MARCELLUS: Yes, absolutely.

The little boy at a carnival — who suddenly vanished.

JIM RYAN: The innocence that we had as a community was changed from that day on.

Everyone was touched by this case, from the parents who swore never to lose sight of their children again.

KEITH HACKETT: I went home, I hugged my kids. I felt so bad.

To the tireless detectives who searched and labored, losing hope they would ever find answers.

MARY ROBILLARD: I have nightmares every May 25 when he disappeared.

Thirty years of twists and turns.

SIBILE MARCELLUS: It’s like mystery on top of mystery on top of mystery.

And then, just a few months ago, the case suddenly came to a dramatic and controversial end.

SIBILE MARCELLUS: That we didn’t see coming.

LINDA HISEY: I screamed. (EMOTION) And I got on my knees.

ANDREA CANNING: This is one of the most shocking twists — for the end of a case that I’ve ever seen.

KEVIN SKOLNIK: Yes. Unbelievable.

Watch “Dateline: The Blue Blanket Mystery” Friday at 9 p.m. on NBC4.

About ‘Dateline’

“Dateline NBC” is the longest-running series in NBC primetime history and is in its 32nd season. Dateline is anchored by Lester Holt and features correspondents Andrea Canning, Josh Mankiewicz, Keith Morrison and Dennis Murphy.

The stories range from compelling mysteries to powerful documentaries and in-depth investigations. When major news breaks, they go to the scene, putting the pieces together to bring the viewer the full picture. And in every story they tell, they help the real people who lived the events share their journeys with the viewer.