The 16-year-old is "sorry and distraught" over the murder of his mother and step-father, his legal representative said on Thursday.
According to police, who spoke to press on Thursday, the boy's 17-year-old friend carried out the murder with "unprecedented brutality" at the request of the 16-year-old, who allegedly promised him money in return.
The bodies of the murdered couple, who have been named by Italian media as restaurant owners Nunzia Di Gianni, 45, and 59-year-old Salvatore Vincelli, were found at their home on Tuesday. Both had head injuries and had been covered in plastic bags.
It was Di Gianni's son who reported the murder to police, initially claiming there had been a robbery. But after almost ten hours of questioning, police said the boy confessed his complicity in the killing, and directed police to a nearby river where the murder weapon - a metre-long axe - and bloodied clothing had been hidden.
The boys are being held in a youth detention centre in Bologna, but are likely to face charges of aggravated murder due to the fact that the crime appears to have been planned.
"I don't know what the investigators are thinking," the boy's lawyer said, as reported in La Nuova Ferrara. "But for me he is someone who needs help."
She added that the motive was not an argument over bad school grades, following a police press conference in which prosecutors noted that the boy had recently quarrelled with his mother over poor school performance.
The reasons, according to the lawyer, are "much more complex" and related to "problems which had not been treated in the necessary way, by him, by the school or by society."
The family lived in Comacchio, near Ferrara, though a few months later the son had moved in with his older friend.
According to Il Corriere, the father of the 17-year-old said he would "never abandon" his son.