On the Saturday of Labor Day weekend, 1974, the Cowden family, which consisted of Richard Cowden, 28, Belinda, 22, David, 5, and Melissa, 5 months, made a spontaneous decision to go camping at one of their favorite spots, Carbury Creek, 40 miles to the Southwest from where they lived in White City, Oregon. They packed the truck then stopped off at the General Store in Copper, Oregon to visit Belinda's mother, Ruth Grayson. Ruth offered to have the family over for lunch the next day, Sunday. The family agreed and set off.
But when the next night rolled around and Ruth still hadn't heard from her daughter and her family, she made the mile drive to go look for them. What she found was concerning. Melissa's diaper bag and fishing poles were next to some trees. Richard's wallet and watch were on the ground, along with Belinda's cigarettes. And some milk and water had been left out on a picnic table. There was no sign of the Cowden family.
A search began that same day and lasted for months. Until finally, half a year later, the family's bodies were discovered near and inside an old mining cave. But who would do such a thing? And what sort of depraved killer would have wanted a young, innocent family dead?

Show Notes:

https://www.imdb.com/title/tt22138532/

https://www.goodreads.com/book/show/6372106-but-i-trusted-you-and-other-true-cases