A sudden moment of terror launches a frantic search for a costumed killer. Reported by Josh Mankiewicz, “Internal Affairs” is a story about bad choices, a fatal attraction and people who proudly wore badges at work -- while living lies at home. Follow now to get new episodes weekly, or subscribe to Dateline Premium on Apple Podcasts for early access and ad-free listening: apple.co/datelinepremium

When a wife and mother is murdered in Greeley, Colorado, responding investigators suspect the costumed killer is someone they know.

A secret affair gets discovered, and a murder suspect gets cuffed.

Choices about relationships, revelations and reconciliation set a murder in motion.

A detective plays cat and mouse with an unusual suspect, while crime scene evidence raises questions for investigators.

Recorded phone calls from a suspect in jail reveal the ties that bind unraveling.

A woman at the center of the case turns state’s evidence and the defendant takes the stand.

As a special preview, we are sharing the trailer for Season 4 of our award-winning podcast, Dateline: Missing in America, which returns with all-new episodes and compelling new cases.

Correspondent Josh Mankiewicz reports on missing person cases brought to Dateline’s attention by our social media followers. Each of the 6 episodes centers on one individual’s disappearance, told through the voices of those left behind. Listen closely. You could be the key to solving a mystery. Details shared by loved ones and investigators may spark a memory that could help bring answers.

Follow Dateline: Missing in America now and don’t miss Season 4, premiering Tuesday, June 10.