A seven-year-old boy who was repeatedly stabbed as he walked home from school last week, died on Tuesday in a hospital in eastern France.
Lucas went into a coma after the attack on October 15 in Joeuf by a man with psychiatric problems and succumbed to his injuries later, prosecutors said.
His attacker, aged 30, had a previous conviction for violence but was not considered dangerous and had not received specialist care, reports said.
Residents staged a march in support of the family during the weekend.
Joeuf, a small town of 6,700 people north-east of the city of Metz, was plunged into mourning after the attack.
Mayor Andre Corzani said everything would be done to help the family in the wake of Lucas' death.
The man arrested after the attack had initially fled the scene after he was tackled by an off-duty policeman, but later handed himself in to local police. He was formally placed under investigation the following day.
He was described as suffering from psychiatric troubles, although experts said his judgement was not completely impaired.
