Sheriff Steve Mansfield announced Tuesday afternoon that deputy Chris Fulton was leaving the department, effective immediately.
Fulton, a 31-year-old Napavine resident, had been on administrative leave since his January 4 arrest. He was off duty and driving his personal vehicle around 12:45 a.m. on I-5 in Chehalis when he was stopped by a Washington State Patrol trooper.
Fulton was arrested but not booked into Lewis County Jail, which is common practice, State Patrol spokesperson Bob Calkins said after the arrest.
Mansfield said Fulton chose to resign instead of facing internal sanctions.
"In looking at the totality of the circumstances surrounding this situation, the most likely administrative sanction he was facing was termination," he said in a news release.