Teddy Bryan admitted Thursday in Grays Harbor County Superior Court that he stabbed 22-year-old Jon Favro, but said he did not intend to kill him.
The two had argued over a girl at a party July 14 in Hoquiam.
KXRO reports the prosecutor is asking for a maximum sentence of 18 years when Bryan is sentenced next month in Montesano for second-degree murder.
Favro, who worked as a corrections officer at the Washington Corrections Center in Shelton, was parked with the young woman when Bryan punched and stabbed him.
After the stabbing, Favro drove off and crashed into a rock embankment, then ran away from the wreckage, only to succumb to his stabbing injuries in a nearby back alley.
Meanwhile, Bryan returned to his girlfriend's home to wash off the knife and change clothes, police said earlier.
Meanwhile, an officer spotted the car's wreckage and discovered that the car's air bags had deployed, but no one was inside. He then spotted blood on the air bag and car door.
Additional officers from Hoquiam and Aberdeen responded to the area. While they were checking the area for possible victims, a woman contacted police and said she had received a call from her 16-year-old son who told her he was "going to do something terrible."
The woman directed police to Bryan's location, about a block away from the crash scene.
Officers spoke to Bryan, who admitted stabbing the driver and the driver had then sped off in the car, according to police. Officers then found Favro's body in the alley.