Imagine you’re a police detective. You’re called to the home of a 41-year-old deceased woman. The first thing you see is the deceased woman surrounded by rose petals. Your first thought is of a jilted lover, right? Wrong.

Have you ever been told you talked in your sleep? Should what you said be reliable?

In February 1974, a 25-year-old artist set off on a trek hitchhiking to an art show. It was a little over a five-hour drive. She didn’t make it far.

In 2005, a 36-year-old man worked at his family’s restaurant. In 2007, he was on trial for breaking into a young woman’s home. The...