The scope and scale of the investigation into the attacks in Norway that left 76 dead was so large that a trial was not likely until next year, the head of the Norwegian Prosecuting Authority said Thursday, dpa reported.
Anders Behring Breivik has been charged with the bombing in the city that killed eight people, and the subsequent attack on the nearby Utoya island that killed 68 people on Friday. He was remanded in custody Monday and is to undergo a psychiatric evaluation.
The acts constituted terrorism since they were aimed at instilling fear in the public at large, the prosecution has said.
"The charges will not be completed before the year-end," Tor-Aksel Busch told public broadaster NRK, adding he "hoped" a trial could be held during 2012.
Busch said that "out of respect for the dead and next of kin the perpetrator must be tried for each killing," and this would require sufficient documentation.
He told NRK the authorities were considering whether Breivik could be charged with crimes against humanity. The maximum sentence for such crimes is a 30-year prison term.
Police are analysing security camera footage of the suspect taken just minutes before the bomb exploded to analyse his movements in Oslo and roads leading in and out of the capital, according to Aftenposten.
Bomb experts say the car bomb near the government headquarters could have caused even greater damage were it not for an underground passage that reduced the effect of the bomb. The bomb left a crater estimated to be several metres in diameter and four metres deep.
"This saved many lives and prevented even greater damage to buildings," bomb expert Per Nergaard told the Oslo daily VG. He said he believed Breivik used a fuse that gave him one minute and 15 seconds to leave the scene.
Authorities are also studying the 32-year-old Breivik's computer and his online activity prior to the attacks.
"We are working round the clock to secure this material," said Odd Reinar Humlegard, head of the country's criminal police.
The rental car used in the bombing had led police to Breivik. The Volkswagen Crafter is believed to have been parked in the greater Oslo area on July 20, two days before the bombing, technical journal Teknisk Ukeblad reported.
Another vehicle used by Breivik to reach the island following the bombing, was meanwhile registered as having passed a road toll the next day.