Police have kept secret for operational reasons what is known about Breivik's exact movements in the run-up to the bombing in Oslo and shooting rampage in Utoya island that killed at least 76 people last Friday.
But Teknisk Ukeblad – an engineering publication – obtained readouts from the city's congestion charge system that registered the movements of two vehicles hired by Breivik. Norway has one of the most advanced systems of road tolls in the world, with a network of sensors and cameras around major cities.
Breivik built the bomb that brought devastation to the centre of Oslo in the remote farmhouse he had leased 100 miles from the capital. It appears that he bought 32 litres of aviation fuel from two different stores last September. It can be used as an ingredient in a bomb.
Last week, Brevik hired a Volkswagen Crafter van and a Fiat Doblo minivan, planning to use the VW to carry the bomb and the Fiat as his getaway vehicle.
According to sources, a roadside sensor at Ulven on the east side of Oslo registered the VW van passing into the city at 10pm on Wednesday, July 20. It is not known where it was parked.
The bomber took a train back to Rena, the village near his farmhouse, just after 1pm the next day and caught a taxi back to his home. The taxi driver remembers laughing and joking with him. At 11pm that night, the grey Fiat hired by the 32-year-old far-Right extremist was registered driving into Oslo to the east.
At 11am the next day, the Fiat was captured by a sensor at Skoyen, in west Oslo, a few minutes from the apartment of Breivik's mother, driving into the centre. Four hours later, the VW passed the same spot. It was parked at the entrance to the prime minister's office by 3.20pm, just two minutes before the bomb went off.
CCTV is said to show Breivik walking straight from the VW and getting into a car behind Marguerite Church.
He parked the Fiat around the corner from the bombing site with his guns in the trunk, went back to his mother's apartment and got the VW car bomb.