A killer was on the loose… The full story tonight at 9/8c on a Dateline Weekend Mystery on NBC. | Dateline NBC

This week on a new Dateline: True Crime Weekly, we’ve got updates on the accused Gilgo Beach serial killer, the Florida grandmother accused of helping plan a murder, and a homicide investigation in the desert. Listen now: https://podcasts.apple.com/us/podcast/the-family-matriarchs-defense-a-landmark-decision/id1745566056?i=1000724861749 | Dateline NBC

Thirty-two years ago this month, a series of murders began near and along Virginia’s Colonial Parkway. When it was over, four couples were dead at the hand of what authorities believe could be a serial killer. The crimes were dubbed “The Colonial Parkway Murders.” | Dateline NBC

Heidi was missing. | Dateline NBC

Even today just say the name "Heidi Allen" and a swirl of memories come back. | Dateline NBC

It was a plot so sinister, so stunning, it took even seasoned detectives by surprise… Tonight at 9/8c on a classic Dateline Weekend Mystery on NBC. | Dateline NBC

“It was horrible. Worst thing I've ever seen.” The full story, tonight on an all-new 2-hour Dateline mystery at 9/8c on NBC. | Dateline NBC