Noah Matlack pleaded innocent Thursday in Benton County Superior Court in connection with last year's stabbing death of Michael Edwards in Benton City.
His trial was set for Sept. 2.
He is accused of stabbing Edwards 26 times in the parking lot of a church in Benton City.
A neighbor found Edwards' body eight hours later behind a shed.
Matlack's accomplice in the attack, Noel Gonzalez, pleaded guilty in February for his role in the stabbing and was sentenced to 13 years in prison.