The shoe and foot were found Tuesday afternoon and turned over to the Medical Examiner's Office by employees of the Port of Seattle Police Department.
The size 10 1/2 sneaker is white with blue trim. County officials say the model first became available for sale in April 2008. A black, cotton Hanes brand sock was also on the foot.
Investigators don't know the sex, age or ancestry of the person who lost the foot, and now they're asking for help from the public to get to the bottom of the mystery.
Anyone with any information about a missing person who may have worn the shoe is asked to call the King County Medical Examiner's Office at 206-731-3232, ext. 1.
Additionally, anyone aware of a missing person who has not been reported is asked to file a missing persons report with the appropriate local law enforcement agency.