It was in mid-August that the 22-year-old was arrested after being overpowered by mosque visitors. Shortly thereafter, the police found the suspected terrorist's step-sister, who was adopted, dead.

The Oslo Police have now received the autopsy report, reports NRK. According to the report, the 22-year-old shot his step-sister with a total of four shots. All the shots were deadly and fired in quick succession.

"The background is that she was of Asian origin"

The police now also go out with the motive: according to them, she was murdered for being Asian.

- We have now been confirmed that the background to the murder is that she was of Asian origin. This is supported by the prosecution's statement and by technical evidence that shows that she did not resist, prosecutor Pål-Fredrik Hjort-Kraby tells NRK.

The murder weapon was in the car outside the mosque

Earlier, the police had several theories about the motive, one of which was that the sister discovered the 22-year-old's plans and tried to stop him.

Police have also determined that the murder weapon is a .22 caliber rifle lying in the 22-year-old's car that was parked outside the al-Noor Islamic Center, the mosque attacked by the then 21-year-old Norwegian.