Diane Kay Sierra was 52 when she was last seen in Sacramento, California, on September 30, 2008. Her disappearance is officially recorded in the National Missing and Unidentified Persons System as case MP146498. NamUs confirms her last known location and date of contact and lists demographic and physical descriptors, but provides no narrative about what happened before she went missing, no clothing or medical details, and no named persons of interest or public leads.

The case remains open with Diane listed as missing and her NamUs entry intended to keep the case accessible to investigators, family and the public.