Officers responded to the scene, in the 2700 block of Westlake Avenue North, at about 8 p.m. after receiving a report of an accident involving a pickup truck and a bicycle.
A preliminary investigation found that the 56-year-old suspect was driving south on Westlake Avenue in an older pickup truck as the bicyclist, a 29-year-old woman, was heading north.
The truck made a left turn directly in front of the bicyclist, who was unable to stop in time. She slammed into the pickup and was thrown from her bicycle.
During the crash, the woman's left thumb was severed at the base of her fingernail. She was taken to Harborview Medical Center for treatment.
A police expert evaluated the 56-year-old pickup driver and observed signs of impairment. A blood draw was taken and police found that the man had a prior DUI conviction. He was arrested and booked into the King County Jail for investigation of vehicular assault.
The investigation continues.