The case stems from the killing of 20-year-old Abbas Rezai, who was found dead in an apartment in Högsby in southern Sweden in November 2005.
Police revealed at the time that Rezai had been scalded with hot oil, hit with a variety of objects, and repeatedly stabbed in the back and chest, with the majority of the wounds sustained after his death.
He was also almost entirely scalped and one of his fingers had been partially chopped off.
The man was allegedly killed because of his relationship with a 16-year-old girl.
Her brother, who was 20 at the time, was convicted, whilst the girl's parents, who were initially implicated, were acquitted, despite police claiming that it was almost impossible that the 20-year-old could have acted alone.
Speaking to the Kalmar District Court on Monday however, Deputy Chief Prosecutor Kerstin Eriksson repeated allegations that the the parents were also involved in the killing and called for all three members of the family to be deported to Afghanistan.
The mother and father, 45- and 47-years-old respectively, sat in court together in front of their son, and denied the charges via their lawyer.
Eriksson claimed that upon initially hearing that their daughter had left home with Rezai, the parents had threatened both with physical harm, but then changed tactics and instead lured them back to Stockholm by apparently granting their approval of the relationship.
However, according to the prosecution, this feigned consent was actually part of a plan to murder Rezai.
The court heard that the girl's brother had borrowed a knife from neighbours and hidden an iron pipe which would be used in the planned attack in the apartment.
The court then heard that the young couple were taken to separate apartments in Högsby where Rezai was repeatedly attacked by both the girl's parents and their son.
Eriksson explained how Rezai was verbally attacked by the father, while the mother warmed oild in the kitchen.
She then went up to the 20-year-old carrying a kettle of hot oil.
"From close range, maybe one metre, she then threw the oil in his face," said the prosecutor.
Eriksson went on to say how Rezai rushed out to the hall blinded, where the mother then held him down and the father started to hit him, first with a baseball bat and then with an iron pipe.
Having killed Rezai, the family then fled to Denmark, before it was agreed that the son should take sole responsibility for the attack and he returned to Sweden.
However, after his conviction, the son changed his story, now pointing the finger of blame at his parents for the murder.
The latest claim is supported by confessions from his sister and brother, while another relative in Denmark has also claimed that the son of the family wrongly convicted as the sole perpetrator.