His murder stirred debate on anti-Semitisim in France after police initially refused to consider the case as a hate-crime.
Hamili's family's lawyers insist he was targeted because he was Jewish.
Isabelle Coutant-Peyre, Fofana's lawyer, told the court her client was not "the devil" but had been the victims of a "political and religious marketing campaign".
Halimi went missing in January 2006 while on a date he had met at his workplace - a Paris mobile phone shop.
The girl lured Halimi to the basement of a building, where he was attacked and subdued.
His murder came month after France's high-immigrant suburbs exploded into rioting in late 2005.
Tens of thousands of people took to the street to protest anti-Semitism some two weeks after his body was found.
The trial is being heard by a juvenile court because two of the defendants were minors at the time of the crime.