Someone called the police at roughly 9:30 p.m. to say a deputy was hunched over his steering wheel and unresponsive in a Starbucks parking lot near Newcastle Way and Coal Creek Parkway, according to Sgt. Cindi West King County Sheriff's Office.
Another deputy -- along with a sergeant and a captain -- responded to the scene and was able to rouse the passed out deputy.
West said alcohol does not appear to be a factor in the incident, but a drug recognition expert from the Bellevue Police Department was called in to investigate. That officer believes the deputy was under the influence of some sort of drugs, possibly a narcotic, according to West.
The deputy, a 46-year-old who's worked for the sheriff's office for 15 years, was arrested on suspicion of physical control of a motor vehicle, which is the legal equivalent of a DUI when no driving is observed.
Several baristas at the Newcastle Starbucks said the deputy was a regular at the coffee shop. One worker said the deputy often flirted with the baristas and "talked about partying."
He was processed at the Bellevue Police Department and released.
Deputies got a search warrant for a blood draw, and they hope to get a warrant to search the patrol car later this week.
The King County Sheriff's Office will conduct an administrative investigation and Bellevue Police will handle the criminal investigation.
The deputy will remain on administrative leave pending the outcome of the investigations.