Anders Behring Breivik, the man who killed 77 people in a bomb attack and gun rampage just over a year ago, was found to be sane Friday by a Norwegian court, as he was sentenced to 21 years in prison.Breivik was charged with voluntary homicide and committing acts of terror over the attacks in Oslo and Utoya Island on July 22, 2011.The issue of Breivik's sanity, on which mental health experts have given conflicting opinions, was central to the court's ruling.Breivik, who boasts of being an ultranationalist who killed his victims to fight multiculturalism in Norway, wanted to be ruled sane so that his actions weren't dismissed as those of a madman.He says he acted out of "necessity" to prevent the "Islamization" of his country.But prosecutors had asked that Breivik, 33, be acquitted on the grounds of insanity, in which case he would have been held in a secure mental health unit.The unanimous verdict was delivered at Oslo district court by a panel of five judges.Breivik, dressed in a dark suit and tie, had a slight smile on his face as the decision was given.He was sentenced to the maximum possible term of 21 years and was ordered to serve a minimum of 10 years in prison. The time he has already spent in prison counts toward the term.In the course of the 10-week trial, which wrapped up in June, the court heard chilling evidence from some of those who survived Breivik's shooting spree on Utoya Island, in which 69 people died -- most of them teenagers attending a Labour Party summer youth camp.In his own testimony, given without any display of emotion, Breivik recounted firing more bullets into teenagers who were injured and couldn't escape, killing those who tried to "play dead" and driving others into the sea to drown.His fertilizer bomb attack against government buildings in Oslo also killed eight people and injured many more.He blamed the Labour Party for promoting multiculturalism in Norway.Breivik has been held in Ila Prison since his detention after the killings.Defense lawyer Geir Lippestad has previously said it is important to Breivik that people see him as sane so they don't dismiss his views.During his trial, Breivik promised that he would not appeal if a court finds him sane and guilty. He is likely to appeal if he is acquitted on the grounds of insanity.Breivik's rampage, the worst atrocity on Norwegian soil since World War II, prompted much soul-searching.Norwegians reasserted their commitment to multiculturalism and tolerance at a series of mass public tributes held in the immediate aftermath of the massacre.And earlier this month, Norway's chief of police stepped down after an independent commission detailed a catalog of police and intelligence failures.It concluded that those errors cost police 30 minutes in getting to Utoya, and that dozens of lives might have been saved.Speaking last month on the anniversary of the killings, Prime Minister Jens Stoltenberg urged Norwegians to "honor the dead by celebrating life," and said Breivik had failed in his attempt to change Norway's values.