And investigations are speculating the murder could have been accidental.
Police received reports of shots coming from a car toward a home in the 1000 block of 102nd Street around 1:20 a.m., said Sgt. Cindi West with the King County Sheriff's Office.
When deputies arrived, they found a man shot to death in the passenger seat of the car out front, and the driver with a gunshot wound to the head. He was rushed to Harborview Medical Center where he later died.
Police thought based on witness reports there was another car involved in the shooting, but investigators have since concluded the driver was the lone shooter, West said.
Detectives believe the driver was upset after recently breaking up with his girlfriend and was going around with his friend shooting at homes connected to where she might be located, West said.
The passenger's seat was found fully reclined, leading detectives to believe the passenger was leaning back to allow the driver to fire through the passenger-side window.
"We think it's possible that he might have been leaning back for the driver to shoot out a passenger window and maybe sat up at the wrong time and got shot," West said. Detectives think the man then turned the gun on himself.
No one else was hurt.