The driver's vehicle was seized, and the investigation is ongoing, Snohomish County sheriff's spokeswoman Shari Ireton said Tuesday.
Police did not release the age or gender of the driver.
The crash happened about 11 p.m. Aug. 4 along Index-Galena Road, near Fifth Street.
Stacey Lain Broyles, 47, of Index, was walking with his dog at the time. Both died after the accident.
Police are hoping to find another vehicle that may have been in the area at the time, Ireton said. It was described as a white van with rack on top.
Anyone with information should call 425-388-3845.
More Local News Headlines
Three weeks out, only four 911 texts have been valid County deputy director named president of state engineers association Accident victim has endured, thanks to his family, police officer Crews try to save man pulled from Stillaguamish River 4:03 p.m. State’s oldest full-time worker on the job at EdCC Lord Hill levee repairs to start July 29 Less than a week before election, only 9.1 percent of ballots returned Red Cross on the lookout for heroes
Our new comment system is not supported in IE 7. Please upgrade your browser here.