In a crime that outraged Germany, the 24-year-old, identified as Ahmad-Sobair O., killed his sister Morsal on May 15, 2008, a day after she approached welfare officials in Hamburg for protection from her brother. He said he had objected to the pretty schoolgirl's lifestyle, her clothing, and her attempts to distance herself from her family.

The case gained nationwide attention, amid a controversy over whether Muslim immigrants were importing the archaic central Asian custom of honor killing to Germany.

The term refers to a Muslim daughter being executed by the males of her own family, who jointly decide she has disgraced the family's honor through her sexual behavior. However, Muslim women have been killed by their families for things such as refusing to enter into an arranged marriage, wearing Western clothing, or even on the basis of rumors about her behavior.

The defense rejected the honor-killing explanation, contending that the immigrant family had been simply dysfunctional. O. admitted the stabbing after his arrest, but declined to testify in court. A court-appointed psychologist said O. had a personality disorder that made his temper uncontrollable.

Prosecutors, who had sought an exemplary sentence to deter future honor killings, asked in vain for the psychologist to be dismissed and a mistrial declared.

Morsal was stabbed to death in a Hamburg parking lot

Defense lawyers welcomed the psychologist's testimony. They said O. killed his sister in a fit of sudden passion and did not deserve the most severe penalty. Defense lawyer Thomas Bliwier denounced the "politicking" in Germany over the case.

Witnesses said Morsal and her brother had a relationship that was a mix of love and hatred, with the spirited, fun-loving girl refusing to bow to her domineering older brother.

Defendant showed remorse in court

Morsal, who had won a civic prize for setting up a peer-counselling project at her school, had complained several times to youth-aid counsellors about her brother and parents. The brother killed Morsal after seeing her walking with boys and being told by his own friends that Morsal would become a prostitute.

Just before the trial ended, the defendant, who had several previous convictions for assault, suddenly burst into tears and sobbed that he had never meant to kill Morsal.

"She was my own sister," he shouted.

German campaigners against honor killings demonstrated outside the courtroom. Heidemarie Grobe of the group Terres des Femmes insisted that Morsal's death fitted the honor-killing pattern.

"It's fixed in the roles inside the families," she said. "The brother usually claims the monopoly of force over the sister."

Terre des Femmes estimates 50 women have been killed in the past decade in Germany for reasons of supposed honor.