They knew each other beforehand and according to the prosecutor, a conflict over joint business ventures may be suspected to lie behind the killing in the 48-year-old's home last year on May 31.
The younger man was so badly injured with a hammer that it took weeks before it could be established with certainty.
The convicted murderer has claimed that he did so in self-defense. According to him, he was demanded money by the 20-year-old and he has also said that he was prevented from leaving the apartment.
The Court of Appeal sees it as an aggravating circumstance that the 48-year-old attacked the 20-year-old from behind when he was lying down on a sofa.
"He has in principle ambushed him and attacked him in a way that meant that the 20-year-old had difficulty defending himself", writes in a press release. But there are also mitigating circumstances and therefore it will not be a life sentence.
The man is also ordered to pay approximately 275,000 kronor in damages to the 20-year-old's relatives.
