Oslo, Norway (CNN) -- The man accused of killing 77 people in Norway last summer will undergo a new psychiatric evaluation, justice officials said Friday, after an earlier test found him to be insane.
Judge Wenche Elizabeth Arntzen told reporters Friday that the court wanted a second opinion because of the importance of the question of his sanity to Anders Behring Breivik's trial, due to start in April.
This was not a criticism of the previous report, she said.
Breivik has been assigned two new psychiatrists to carry out the evaluation, court spokesman Geir Engebretsen told CNN.
The decision follows requests from the families of some of the victims, amid wide public debate in Norway over the initial psychiatric report, he said.
In November, prosecutors said psychiatrists had determined Breivik was psychotic at the time of the attacks and during 13 interviews experts conducted with him afterward.
The ruling meant he cannot be sentenced to prison or preventive detention, but he can be confined to a mental hospital for the rest of his life, prosecutors said.
The two judges hearing the case, Arntzen and Arne Lyng, decided to order another evaluation to ensure that all the necessary evidence is presented during the trial, Engebretsen said.
The psychiatrists are likely to start their interviews with Breivik in the next few days, he said. Breivik has told his lawyer he will not cooperate with another evaluation.
Prosecutors reported that prison staff and health workers had not seen evidence of psychotic behavior from Breivik, Arntzen said, as she gave the court's decision.
The newly appointed psychiatrists will be able to watch video recordings of police interrogations and previous psychiatric interviews with Breivik to make sure they have the full picture, Arntzen added.
Breivik is accused of killing eight people in a bomb attack in Oslo and 69 more in a gun rampage on nearby Utoya Island. The latter were among 700 mostly young people attending a Labour Party youth camp on the island.
He has pleaded not guilty but admits carrying out the July 22 attacks, the judge handling his case has said previously.
The trial, due to begin on April 16, is expected to last 10 weeks.
In the previous evaluation, doctors found Breivik to be paranoid and schizophrenic, prosecutors said. The experts reached their conclusions after 36 hours of interviews with Breivik.
He has been in custody since his arrest on Utoya Island on the day of the killings, which marked the deadliest attack in Norway since World War II.
He now has access to the internet and other media, after a period during which he was kept isolated from the world, Engebretsen said.
CNN's Laura Smith-Spark and Bharati Naik in London and journalist Olav Mellingsaeter in Oslo contributed to this report.