Holly Grigsby and David "Joey" Pedersen, who said he was a member of the "Aryan Soldiers" prison gang, were charged in connection with the killings of Pedersen's father and stepmother in Everett, Wash., an Oregon teenager and a California man.
Grigsby pleaded guilty in federal court Tuesday to racketeering charges connected to the four killings.
Pedersen previously pleaded guilty in state court to murder in the slayings of his father and stepmother. On Tuesday in court, Grigsby denied wielding the knife that killed Pedersen's stepmother, but acknowledged her part in the conspiracy.
"Did you in fact stab her to death?" U.S. District Court Judge Ancer Haggerty asked.
"No," Grigsby replied.
"You're saying the other co-defendant (Pedersen) did that?" Haggerty asked her, before her lawyer intervened.
Haggerty asked again about the nature of her actions, and she responded in a voice so low that he asked her to repeat herself.
"I have nothing to say about Joey," she said.
The federal charges stem from the incidents crossing state lines - Pedersen and Grigsby allegedly took Pedersen's father's car across the Washington-Oregon state line and similarly crossed into California from Oregon in a stolen vehicle.
Under the agreement, Grigsby will not be prosecuted in state court in Oregon, Washington or California. Pedersen is to be tried on federal charges in U.S. District Court in July.
Attorney General Eric Holder decided not to seek the death penalty.
Prosecutors read from letters they said Grigsby sent to Pedersen's fellow white supremacists in prison. In them, Grigsby acknowledged that the slayings wouldn't individually further the cause of white supremacy, but could "light the spark" of a revolution.
In those letters and others sent by Pedersen, the two said their motives were to cleanse the country of Jewish and Zionist influences. Pedersen carried a pre-written press release that Grigsby said was to be used if they attacked Jewish religious and community centers in Portland.