Circumstances of Disappearance
Anna Waters was last seen between 14.00 and 14.15, playing in her family's backyard in San Mateo County, California on January 16, 1973.

In the beginning of the investigation, it was theorized that she had fallen into Purisima Creek, located near the family's home, and drowned. The area around the creek and the waters were searched but no trace of Anna was found.

With time, investigators and her family started to suspect foul play was involved in her disappearance. Her stepbrother told his family he remembered a strange couple driving alongside Anna, trying in vain to tempt her into the vehicle.
Anna attended kindergarten at Hatch Elementary at the time of her disappearance.