According to the court, the 38-year-old threatened the bus driver without provocation, telling hum he would "bite off his fingers", "smash his nose," "put out the eyes" and "tear off his hair."
He then attacked him, beating him continuously for several minutes and biting off a piece of skin roughly the size of a matchbox, which the police believe he then swallowed.
The two passengers on the bus called the police, who eventually came to the driver's rescue. One of the passengers told The Local that it would have been futile for them to intervene personally, as the attacker was "a really big man" and would have overpowered them.
According to the passenger, the driver remained remarkably calm in the face of his ordeal.
"Afterwards we could see that the driver was missing quite a big part of his skin. It was quite dramatic. But he was quite calm, and they sent some doctors to take care of him."
According to the court, the driver spent three days in hospital after the attack, and required plastic surgery to repair the missing skin.
The attacker told the police after he was arrested that the bus driver, who he appeared never to have met, 'needed to be punished'.
During the trial, court psychiatrists ruled that the man had been sane at the time of the attack, but was suffering from lack of sleep and the after-effects of a period of heavy drinking following the break-up of a relationship.
Although the judges were divided, a majority agreed that he had not been psychotic at the time of the attacks, making him liable for a jail sentence.
The day before the attack, the man had been seized by the police and checked into a mental health unit, following a tip off from his family, who were concerned by his erratic behaviour.
The man had refused to let the police into his home, declaring: "This is the house of God. I am God".
When the police tried to immobilise him with pepper spray, he reportedly wiped the spray from his face, before declating, "have you not got anything better than that?"
Police then sent in a police dog, which the man attacked, pressing his fingers into its eyes and prying open its jaws with his bare hands.
According to Aftenposten, the dog later had swollen eyes and a limp. The man has also been convicted of violence against a police dog.