The San Mateo County sheriff's office is looking for a 54-year-old man considered at-risk who hasn't been seen since earlier this month.
Christopher Ryan, 54, who has a medical condition that requires daily medication, was last seen the morning of Oct. 9, according to the sheriff's office.
His sister reported him missing the following day and said it was unusual for Ryan to be out of touch with his family for so long.
Calls from family and law enforcement officials to his cell phone went unanswered, and authorities tried to trace his phone but found it was turned off.
At about 11:30 p.m. Oct. 10, a sheriff's deputy located Ryan's black Acura sedan unoccupied in the Vista Three parking lot near Highway 280 and Highway 92. Ryan's medication and cell phone were found in the vehicle.
Anyone with information about Ryan's whereabouts is urged to call the sheriff's office at (650) 363-4911.
