(NBC News) — On “Dateline,” Fort Worth investigators desperately search for answers after Carla Walker, a 17-year-old high school student, is kidnapped and murdered following a Valentine’s Day dance.

“Dateline NBC” correspondent Josh Mankiewicz reports on the cutting-edge DNA technology and diligent police work that led detectives to identify her killer.

Here’s a preview:

The day of the dance Rodney had finished his shift at a local gas station, gone home, gotten dressed and was heading over in his mom’s Ford LTD to pick up Carla.

JOSH: She looked like a million dollars?

RODNEY MCCOY: Oh yeah. Definitely. T– she– when she dressed up she did it right. And w– with– with her, it really didn’t take that much.

They drove to dinner and then to the dance. The high school cafeteria was dressed up in pink and red. The theme? Love is a Kaleidoscope. Come on, it was high school.

KRISTI SHELTON: Had a great time. Danced the whole night. I remember Carla and Rodney coming in we were all dancing on the floor together.

Rodney and Carla seemed as in love as two teenagers could be. A couple of months earlier, Rodney had given Carla a promise ring.

RODNEY MCCOY: It meant a lot to me. It meant, “I’m here, I’m yours, and I promise you.”

Back at the Walker house, Carla’s mom and dad were playing dominoes with relatives.

Her big sister, Cindy, and her little brother Jim were watching TV. It got to be 1 a.m.

JIM WALKER: And– I heard a car hitting a curb– And then I heard Rodney’s voice outside yelling, “Mr. Walker, Mr. Walker. Help me.

CINDY: Little bit after that, the front door just pounding. You know, pound, pound, pound, pound, pound. So Jimmy and I both went to the front door together. And opened it. And it was Rodney. And he had– was bleeding from his head down his face. Had blood all over his shirt, just screaming. And I looked over his shoulder, like, “Where’s Carla?” And it’s like, “They’ve got her. They’ve got her. They’ve got her.” And I was like, “Who? Who’s got her?”

You can watch “Dateline: After the Dance” Friday on NBC4 at 9 p.m.

About ‘Dateline

“Dateline NBC” is the longest-running series in NBC primetime history and is in its 30th season. Dateline is anchored by Lester Holt and features correspondents Andrea Canning, Josh Mankiewicz, Natalie Morales, Keith Morrison and Dennis Murphy.

Dateline is the #1 Friday newsmagazine and reaches more than 17 million people every week through its broadcast, and millions more through its social media platforms and podcasts.

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.

This past season, Dateline debuted two new podcasts, “Mommy Doomsday” and “Killer Role,” hosted by correspondent Keith Morrison.

In February, NBC also greenlit a straight-to-series inspired by the story featured in the Dateline podcast series, “The Thing About Pam.” Two-time Oscar-winning actress Renee Zellweger will star and executive produce the series, in collaboration with Blumhouse Television, NBC News Studios and Zellweger’s Big Picture Co.