The teenager says the killing was not premeditated, and wants the conviction changed to serious assault and manslaughter. In Swedish law, a murder conviction requires premeditation to be proven.

Prosecutor Kjell Yngvesson has also appealed the conviction. He argues that the murder was an honour killing carried out jointly by the convicted man and his parents. All three should be convicted of murder, he argues.

Yngvesson says that the family, which like the victim is originally from Afghanistan, was acting to protect its honour after the 20-year old started a relationship with their 16-year old daughter.

The son accepted all responsibility for the crime both prior to and during the trial. He claimed he had defended himself when the 20-year old became aggressive. He admitted assaulting the victim, but said he did not intend to kill.

The Kalmar district court convicted him of murder and sentenced him to four years secure youth detention, followed by deportation with a lifetime ban on returning to Sweden. The parents were cleared of all charges, although two lay judges in the trial wanted both the father and mother to be convicted of murder.

The teenager’s defence counsel Helena Karlsson argues that his sentence should be reduced and that the deportation order should be lifted or the ban on returning to Sweden should be given a time limit.