The disappearance of the Lyon sisters is a 35-year-old mystery that Montgomery County police still hope to solve.

On March 25, 1975, 12-year-old Sheila Lyon and 10-year-old Katherine Lyon vanished from the Wheaton Plaza Shopping Center. Their disappearance gripped the Washington area for the months of April and May 1975, as massive search parties conducted frenzied searches of vacant lots and waterways. On May 23, 1975, Maryland Lt. Gov. Blair Lee called in the National Guard to scour a Montgomery County forest for any trace of the two girls.