Carbonaro was reported missing on Monday afternoon and her body was found early on Wednesday, dumped in a wardrobe in an abandoned building in Afragola, a town in the province of Naples.
The girl was brutally murdered, possibly with a rock, the sources said.
The suspect confessed after being detained in relation to the homicide, according to the sources.
His identity has not been revealed yet, but the fact that ordinary prosecutors are dealing with the case, and not prosecutors for minors, suggests he is at least 18 years old.
Meanwhile, a 29-year-old worker from Robecco sul Naviglio (Milan) has been arrested for the murder of Vasilica Potincu, a 35-year-old woman killed on Saturday evening in Legnano, police said Wednesday.
The woman, who was a sex worker, was stabbed nine times in the apartment where she received clients.
She was the mother of a 14-year-old boy.
Questioned today by the prosecutor Ciro Caramore, who is coordinating the investigation, the 29-year-old availed himself of the right to remain silent.
Italy has experienced an alarming spate of femicides and shocking cases of gender-based violence.
ANSA
