Anders Behring Breivik, who killed 77 people in twin attacks in Norway last July, was Wednesday formally charged with committing acts of terror and voluntary homicide, according to a 19-page indictment presented by prosecutors.

The charges carry a penalty of up to 21 years in prison, though the incarceration can be extended for as long as he is considered a danger to society. If he is found criminally insane he would face confinement in a psychiatric ward instead.