Prosecutors in Norway have asked a court in Oslo to declare Anders Behring Breivik insane and commit him to a mental institution.
Breivik, 33, killed 77 people and injured 242 on 22 July last year when he bombed government buildings in Oslo and young Labour Party supporters at an island camp.
He has admitted killing 77 people last year, but says he should be acquitted on the grounds he was defending the Norwegian people from Muslim immigration.
Court-appointed psychiatrists have come to opposing conclusions on whether Anders Breivik is sane.
The defence concludes on Friday. Judges are due to deliver their verdict in July or August.
Breivik could be seen smiling at times as he listened to prosecutor Svein Holden and shaking his head while he summed up.
Before the trial, psychiatrists commissioned by the court found Breivik insane, suffering from paranoid schizophrenia, and therefore not responsible for his actions.
This caused an uproar in Norway. The court then ordered a second opinion which found Breivik sane, as did a number of other psychiatrists who had observed him in detention and in court.