After a heated argument with her boyfriend during a night out in Green Bay, Wisconsin, 31-year-old mother of three Nicole “Nikki” VanderHeyden stormed away from her friends and vanished into the darkness. She was never seen alive again.

The next morning, her brutalized body was discovered in a secluded field—beaten, strangled, and bearing signs of a violent struggle. Investigators quickly focused on Nikki’s boyfriend, Doug Dietrie. The fight. The delay in calling police. Blood near their home. It all seemed to point in one direction.

But as forensic evidence trickled in and digital data told a different story, the case took a chilling turn. Fitbit records, cell phone location data, and DNA would ultimately expose a man with no connection to Nikki—and a version of the night that ended in sexual violence and murder.

In this episode of Unsaid Case Files, we examine how assumptions nearly destroyed an innocent man’s life, how modern technology reshaped a homicide investigation, and how a woman who simply walked away from a fight crossed paths with someone far more dangerous.