The killers lived next door. They seemed ordinary, decent people.

Italians tried yesterday to come to terms with the news that a middle-aged, born-and-bred Italian couple slit the throats of four neighbours, including a two-year-old toddler whom they said made too much noise.

After a month-long investigation, police this week arrested Rosa Bazzi and her husband Olindo Romano, who lived in the same building and had a long-running feud over noise with the murdered Castagna family. The couple gave a full confession after a 10-hour interrogation.

"We just could not stand them anymore," Rosa Bazzi, a petite housemaid obsessed with cleanliness and quiet told investigators as she confessed to killing the two-year-old with a knife.

"He was always screaming, my head was exploding," she said, according to media reports.

Thirty-year-old Raffaella Castagna, her son Youssef, her mother and a neighbour were found dead on December 11 in the Castagnas apartment in the prosperous northern town of Erba. Their home had been set on fire.

"See how peaceful it is now?" "We can finally sleep well," Mr Romano, a garbage collector, and Ms Bazzi said to each other after the murders, according to investigators who bugged their home.

The case sparked soul-searching by the press, which the day after the murders blamed Ms Castagna's husband, an immigrant jailed for drug dealing and recently freed under a mass pardon.

Rare front-page apologies were offered when it emerged the man was on a trip home to Tunisia at the time of the murders.

"Now that the Erba case has been resolved, we are forced to come out of our cosy homes full of prejudices... and look in the face the killers next door," wrote La Repubblica daily, which dedicated its first six pages to the crime.