William A. White of Roanoke, Va., faces up to 10 years in prison when he is sentenced, federal prosecutors said.
The foreperson, identified by the government only as Juror A, served at the 2004 trial of Matthew Hale, leader of the World Church of the Creator. Hale was sentenced to 40 years for soliciting the killing of a federal judge.
Federal prosecutors said Hale on his Web site posted Juror A's name and home address along with derogatory comments. The site, which used the name American National Socialist Workers Party, earlier had comments about people such as Holocaust survivor Elie Wiesel with the wish that they be harmed.
"While freedom of speech is among our most cherished rights, the First Amendment does not protect anyone who intends to induce others to kill or injure," U.S. Attorney Patrick Fitzgerald said after the verdict. "It is critical to our system of justice that jurors and judges alike must be free to perform their duties without living in fear."
White is already serving a 30-month sentence after being convicted in federal court in Roanoke of witness intimidation. No date has been set for his new sentencing.
Biologists detail four new deep-sea 'killer sponges'
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend