The 88-year-old white supremacist is charged with the murder of Stephen Johns, a security guard at the museum. Von Brunn was shot by other guards after he fired at Johns and remained in critical condition in a Washington hospital Thursday.
In an interview with Fox News Channel, his ex-wife compared him to the character John Wayne played in "The Shootist," an aging gunslinger who "made sure he wasn't going to go out lying down with cancer."
His former wife, who was not identified by name, said she was surprised by von Brunn's violent action. But she said she divorced him because of his extreme hatred of blacks and Jews.
"He would simply constantly berate the Jewish people and black people and it was something that consumed him," she said. "It was all-consuming."
Von Brunn was imprisoned for more than six years after he was arrested at the Federal Reserve Bank with several weapons in 1981. He said he planned to take the members of the Federal Reserve board hostage.