Washington ? A jury convicted a 15-year-old boy of first-degree murder Friday for a brutal attack on a developmentally disabled playmate more than three years ago.

Evan Savoie faces 20 to 26 years in prison for the slaying of 13-year-old Craig Sorger, who was found beaten and stabbed to death Feb. 15, 2003, in a recreational vehicle park.

Savoie, 12 years old at the time of the killing, was among the youngest murder defendants in Washington state to be tried as an adult. He had repeatedly proclaimed his innocence, saying Sorger fell from a tree and that he left him injured on a wooded trail but did not kill him.