Federal agents arrested three men on gun and explosives charges Tuesday, including a white supremacist who once served time for plotting to kill Martin Luther King Jr. (search)

Keith Gilbert, 65, a former associate of late Aryan Nations (search) founder Richard Butler, was arrested at his Seattle home, FBI spokeswoman Robbie Burroughs said.

He and the others arrested — William D. Heinrich, 50, and John P. Hejna, 44 — were ordered held until detention hearings later this week. Court-appointed lawyers for the three did not comment following separate appearances in federal court.

A complaint said Gilbert had sold AK-47 (search) assault rifles and other weapons to a confidential informant working with the federal government over the past two years. He was charged with five counts of being a felon in possession of a firearm, possession of a machine gun and possession of an unregistered gun.

He faces a maximum 10 years in prison and a $250,000 fine on each count.

"The defendants were doing this to make money," said Assistant U.S. Attorney Andrew Friedman. "There is no evidence of any plot to use the weapons or explosives against any target."

Gilbert was arrested in 1965 and convicted of stealing 1,400 pounds of TNT, which authorities said was part of a plot to kill King by blowing up a stage while he spoke at an Anti-Defamation League convention in Los Angeles.

After serving five years in San Quentin for the plot, Gilbert moved to northern Idaho and became involved with Butler's neo-Nazi group. They had a falling out in 1977.

Gilbert was convicted in 1983 of assaulting a teenager from a racially mixed family.

His son, Joshua Gilbert, told television reporters Tuesday his father is "a nice guy" and "pretty laid back. I don't know of any machine guns in the house."

A separate complaint accused Heinrich of selling a pistol to an informant, and Hejna was accused of being involved in selling the plastic explosive C-4.