OSLO, Norway — The self-described perpetrator of one of the worst modern mass murders in peacetime calmly said in court Monday that that he expects to spend the rest of his life in prison for bombing Norway’s capital and opening fire on a political youth group retreat, officials said.

Anders Behring Breivik told the court as he entered a not guilty plea that he wanted to save Europe from Muslim immigration and warned that two other cells of his terror network remain.

Prosecutor Christian Hatlo told reporters Monday that Breivik was very calm and “seemed unaffected by what has happened.” He said Breivik told investigators during his interrogation that he never expected to be released.

Police announced, meanwhile, that they had dramatically overcounted the number of people slain in a shooting spree at a political youth group’s island retreat and were lowering the confirmed death toll from 86 to 68.

The overall toll in the attack now stands at 76 instead of 93. Police spokesman Oystein Maeland said that higher, erroneous figure emerged as police and rescuers were focusing on helping survivors and securing the area, but he did not immediately explain more about how the overcounting occurred.

Police also raised the toll from a bombing outside the government’s headquarters in Oslo before the shooting spree, from seven to eight.

Breivik has confessed to bombing Oslo’s government headquarters and opening fire on the young people at an island retreat.

The court ordered him Breivik held for eight weeks while prosecutors investigate, four of which will be in isolation, saying Breivik could tamper with evidence if released. Typically, the accused is brought to court every four weeks while prosecutors prepare their case, so a judge can approve his continued detention. Longer periods are not unusual in serious cases.