Kiyoshi Higashi butchered Jim Sanders and his family in deadly robbery after he advertised a diamond ring for sale on the popular trading website.
Cops called him the "main player" in the four strong team, three of whom are awaiting trial, who shot Sanders after he broke free and began to fight the robbers.
Detective John Jiminez, the case's lead investigator, described Higashi as "pure evil."
He said: "He's earned every second of every day he will spend in prison."
The 23-year-old was unrepentant in court Friday according to Tacoma's The News Tribune reported.
He said no one but God could judge him and added: "I don't care what sentence you give me," after being convicted of murder, burglary, robbery and assault at Pierce County Superior Cour.