ROME (AFP) - Two Italian teenagers who have confessed to the brutal axe murder of the parents of one of them were regular cannabis users and video game obsessives, it emerged Friday (Jan 13) as the country asked itself what led to the tragedy.

In a case that has shocked a nation famous for its close family ties, the two teens are being held in a child detention centre over the slaying of Salvatore Vincelli and Nunzia Di Gianni.

The restaurant owners in the little village of Pontelangarino near Ferrara in northeastern Italy were hacked to death in their bed at the family home on Monday evening.

Their 16-year-old son, Riccardo, confessed two days later to asking a 17-year-old friend, Manuel, to carry out the killing, according to statements leaked to the media.

Manuel admitted that he applied the fatal blows, striking Salvatore three times and his wife six times with an axe used to chop firewood.

"She didn't want to die," the 17-year-old reportedly testified while his younger buddy told police: "I wanted them dead but I could not do it myself. They were my mamma and papa."

The teens initially claimed to have spent Monday night at Manuel's home but their alibi fell apart under interrogation and they made confessions on Wednesday.

Riccardo was said to have offered his older, more outgoing but poorer friend 80 euros up front with the promise of another 1,000 for carrying out the killing.

Investigators were quoted as having been struck by the young men's relative detachment from the gruesome act they had perpetrated.

"They recounted it as if it was a video game," one was quoted as saying by La Stampa.

Both boys spent hours every night locked in their bedrooms playing on their PlayStation or Xbox consoles, according to friends and family.

Manuel regularly skipped school as a result of his all-night screen sessions. Riccardo attended more regularly but his poor marks led to frequent family fights.

School friends said both boys smoked cannabis on a daily basis while Riccardo had boasted of having experimented with cocaine.

Both Manuel's parents, while admitting that he lived an isolated life, have said he could not have carried out the killings without being under the influence of narcotics.

"He must have taken something because no human being can kill like that in cold blood," his mother told Corriere della Sera.

Riccardo's lawyer said the case had to be seen as society's failure.

"What we are dealing with are adolescent problems not being dealt with adequately," she told La Stampa.

"R. (Riccardo) was vulnerable to violent emotional blockages. He has a huge need of a helping hand."

Under Italy's legal system, the two teens will be tried by a child court, if psychiatric evaluations conclude they can be judged for their crimes.

Some previous child killers have been placed in the care of a community run by well known Catholic priest, Don Antonio Mezzi, who has said he would be willing to look after Riccardo and Manuel for the duration of their sentences.

"Now we are hammering these 'monsters' on the front pages," he said. "But the real problem is that schools and families are not properly prepared for the new challenges of adolescence.

"They have to understand what they have done. Sending them to prison would be an error that would mean losing them for ever."

The Catholic church is to address the challenges faced by young people in the modern world at an October 2018 synod of bishops, for which Pope Francis outlined a provisional agenda on Friday.