Anders Behring Breivik, the man accused of killing 77 people in Norway this summer was declared insane, police said Tuesday.

Breivik has been in custody since his arrest on Utoya Island, near Oslo, on the day of the killings. He is currently being held in isolation in prison and has not been informed of the psychiatric evaluation.

"The conclusion ... is that he is insane," prosecutor Svein Holden told a news conference on Breivik's psychiatric evaluation, according to the Guardian. "He lives in his own delusional universe and his thoughts and acts are governed by this universe."

Brevivik, who has a strong anti-immigrant stance, has previously said he staged what he called “the executions” out of love for his people, according to the report.

Police say he suffers "grandiose delusions" and "believes he is chosen to decide who is to live and who is to die." They also say that a number of psychiatrists had found Breivik paranoid and schizophrenic.

Experts say that Brevivik was psychotic during the 13 interviews conducted with him and at the time of the attacks.

Police say, despite Brevivik’s psychiatric evaluation, he will still be tried to determine whether be committed the murders.

The Guardian reports that if the court accepts the psychiatrists’ conclusions, Breivik will be detained in a psychiatric institution rather than a prison. Under Norwegian law, he cannot be sentenced to prison or preventive detention but can be kept in a mental institution for the rest of his life.

Norwegian courts rarely reject psychiatric evaluations, 36 hours of interviews with Breivik, according to CNN. However courts are allowed to challenge psychiatric evaluations or order new tests, and if found healthy Breivik, will be held in prison, and in the future will have a chance of being released.

Police say if Breivik is placed under a compulsory mental order; an extension of his confinement will be reviewed by a court every three years, according to CNN. The court will then consider whether he still poses a threat to society.

Police say Breivik will be given the opportunity to give evidence at his trial which is expected to start in April.