BERLIN, June 18 (Xinhua) -- The widely-anticipated trial of an Afghan asylum seeker who is accused of murdering his 15-year-old ex-girlfriend in broad daylight opened in Germany on Monday.

Prosecutors believe that the suspect in question killed Mia, a local inhabitant of the town of Kandel, in a knife attack back in December 2017 as a punishment for having recently separated from him.

Shortly before the deadly incident at a drug store, the girl and her father had reported the ex-boyfriend to police on counts of libel, duress and making threats and infringing on privacy.

The public has been excluded from court proceedings, which will occur under juvenile criminal law as the exact age of the suspect is unknown. The Afghan asylum seeker himself indicated being 15-year-old and was consequently treated as an unaccompanied minor when he arrived in Germany.

However, an assessment by the state prosecution office concluded after the murder that the individual must be at least 17.5 years old and more likely around 20 years old.

If the assessment is correct, Mia's ex-boyfriend would have succeeded in alleviating the circumstances of his sentencing by lying about his age. Individuals above the age of 18 are tried as adults under German law and face more severe punishment for criminal wrongdoing.

The case of Mia's murder has consequently sparked a heated public debate over whether the procedures by which German authorities determine the age of young asylum seekers upon arrival, are still appropriate.

The far-right group "Kandel is everywhere" was set up in response to draw attention to the alleged threat posed by asylum seekers to the German native population and drew 4000 protestors to its first rally.

The Landau regional court is expected to reach a verdict in the trial by the end of August.