Chris Kilcullen, 43, who had been a police officer in Eugene for 12 years, was killed Friday in nearby Springfield, KMTR-TV reported. Springfield police are leading the investigation.
Cheryl Dawn Kidd was being held in the Lane County Jail, KVAL-TV in Eugene said.
Springfield Police Chief Jerry Smith said Kidd led police on a high-speed chase on back roads before she was arrested.
A candlelight vigil was planned Saturday for Kilcullen at city hall in Eugene, KMTR said.