(NBC News) — Tonight on “Dateline” two exclusives — first, behind the headlines of the Alex Murdaugh family saga and then, new developments in the disappearance of Kristin Smart who vanished from a college party in 1996.

Beginning at 9 p.m. — a shocking family saga grabbing national headlines.

After his wife and son are murdered, prominent South Carolina lawyer Alex Murdaugh is ensnared in multiple scandals, involving allegations of multimillion-dollar swindles and other mysterious deaths.

Craig Melvin spoke with a reporter who has followed the family for decades.

Here is a preview of Melvin’s report:

CRAIG MELVIN: What did that double murder do– to the community here in Hampton County?

VALERIE BAUERLEIN: It just upends everything in a community like Hampton County. You start to realize quickly that the dynasty that, in many ways, built Hampton County– has exploded with the double homicide and then the quick unraveling of what was the fabric of the community. The Murdaughs are the fabric of Hampton County.

Tonight the family of the Murdaugh’s housekeeper breaks its silence in the first interview since her death, only on “Dateline,” at 9 p.m.

Then at 10 p.m., “Dateline” reports on new developments in the disappearance of California Polytechnic State University freshman Kristin Smart, who vanished after leaving a party in 1996.

In a network TV exclusive interview, Smart’s brother, who is speaking out in his first network interview, and a former student who was at the party Smart attended will speak with “Dateline” correspondent Josh Mankiewicz.

Mankiewicz also interviews insiders close to the case, including “Your Own Backyard” podcast host Chris Lambert and San Luis Obispo County Sheriff Ian Parkinson.

Here is a preview of Mankiewicz’s report:

She loved it here. The pacific — open, free, full of possibility and adventure. Back then, those words also described Kristin Smart.

MATT SMART: It was really just that boundless energy and that boundless determination to live life to the fullest.

Kristin, just 19-years-old.

RACHAEL BYRD: Everybody knew Kristin was there when she walked into a room. ‘Cause she was just tall and gorgeous and legs for days,

A college freshman when she vanished. Now, a quarter-century has passed. It’s a story that grew to more than the sum of its parts. Through the years, through the graduations, Kristin’s presence lingered. Quiet, but constant. In the poster on the highway and on the pathways through the red brick dorms where she was last seen. A kind of ripple effect started long ago and now has resurfaced.

Watch tonight starting a 9 p.m. for two straight hours of “Dateline.”

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.