This Europe: Italy transfixed as pilloried mother released in child murder case

The certainties of millions of Italian armchair jurors in a child murder case that has obsessed the nation have been suddenly and uncomfortably shattered.

Since three-year-old Samuele Lorenzi was found battered to death in his parents' bed in a tranquil Alpine village in January, they have known for sure who was responsible. Within days of the crime the media had given them the pointers they needed, drip-feeding details provided by the investigators in Cogne, near the French-Italian Alpine border. Using the conditional and subjunctive tenses – very handy to avoid libel suits – they made it clear that Samuele's mother, 31-year-old Anna Maria Franzoni, was the killer.

She had left the child alone for eight minutes as she accompanied his elder brother down the hill to the school bus. The possibility of a psychopath, an outsider or a local being the killer were dismissed because of the brief time frame. Much was made of blood spots on the mother's pyjamas and slippers.

Ms Franzoni was detained, though not charged, in mid-March. Under Italian law, suspects can be held in preventive custody.

However, a 68-page ruling from a court in Turin on Tuesday shot to pieces the prosecution's arguments. It said the warrant was based on circumstantial evidence and suggested Samuele could have been stabbed to death by an outsider. The alibis of two neighbours were unconvincing, it said.

The ruling has shaken the hamlet, which has been under siege since January. Daytrippers have been photographed in front of the house but visitors to the ski slopes have given it a wide berth.

The Turin sentence – which dismantles the case against Ms Franzoni point by point – has caused deep ripples. The investigators say they are reflecting on the contents, but in the meantime police have again searched the family home in an effort to find the murder weapon.

"Investigative catastrophe" headlined la Repubblica. It said the belief that Ms Franzoni was guilty had conditioned the investigators' work. In a series of interviews, Ms Franzoni, who is undergoing psychiatric evaluation, said she believed she knew who had stabbed her son 17 times.

Sociologists are trying to explain why the murder has obsessed Italy: taboos about a mother's role, a sense that if evil reaches such an idyllic spot there is no hope, the horror of a child killed in his parents' bed.

But while the mother is no longer demonised, no one is any closer to knowing who killed the child. A survey published yesterday said 53 per cent of Italians believe the killer will never be found.