Police had spent Monday night checking whether Thomas I. had written the comment found under an article published by the newspaper VG. An online anti-racism magazine, Vepsen, had reported that the lay judge used a Facebook profile for his comment. Vepsen tracked the corresponding email address back to him, and also found his portrait photo.
'A Serious Setback'
The editor-in-chief of Expo, a Swedish Internet magazine linked with Vepsen, told Spiegel Online: "That could be a serious setback for the trial."
Three citizens were selected at random to sit with two professional judges on the panel trying Breivik.
The maximum penalty Breivik faces, if found criminally responsible, is 21 years in prison, but this could be extended indefinitely if he is still considered a danger to society after that period.
At the start of his trial on Monday, Breivik, 33, gave a clenched-fist salute, smirked at the court and pleaded not guilty.
Once the trial resumed on Tuesday, Breivik read from a prepared statement and boasted about the killings.
"I have carried out the most sophisticated and spectacular attack committed in Europe since the Second World War," he told the court.
Breivik has said he acted in defense of his own country by setting off a car bomb in Oslo that killed eight people in the government district of Oslo, and then shooting dead 69 people at a youth summer camp organized by the ruling Labor Party.
Intellpuke: You can read this article by Spiegel Correspondent Gerald Traufetter, reporting from Oslo, Norway, in context here: http://www.spiegel.de/international/europe/0,1518,828013,00.html
This article included reporting by various news agencies.