OSLO - The court putting Norwegian killer Anders Behring Breivik on trial for massacring 77 people last year dismissed a lay judge on Tuesday after he posted a comment on a Facebook page saying the gunman should face the death penalty.

The trial against Breivik began on Monday, with two professional judges, as well as three lay judges chosen from civil society, presiding over the court.

Lay judge Thomas Indreboe is seen in a courtroom at the terrorism and murder trial of Norwegian mass killer Anders Behring Breivik, in Oslo April 17, 2012. [Photo/Agencies]

After the killings last July, lay judge Thomas Indreboe posted "the death penalty is the only just outcome of this case" on a Facebook page.

The dismissal is not expected to lead to any mistrial verdict and Breivik is still expected to take the stand for the first time on Tuesday. He has pleaded not guilty, saying he acted in defence of Norway against multi-culturalism.

If found guilty and sane, Breivik faces a maximum 21-year sentence but could be held indefinitely if he is considered a continuing danger. If declared insane, he would be held in a psychiatric institution indefinitely with periodic reviews.