Daniele, 59, died of a heart attack in the early hours of Monday after being rushed from his holiday home in Tuscany to a hospital in Rome.
La Stampa reported that a manslaugter probe into his death has been launched and that an autopsy would be carried out after funeral ceremonies in Rome and Naples on Wednesday.
Sources told Ansa that the investigation will question whether it was the singer’s decision to be taken to Rome after he fell ill on Sunday night.
The news agency reported that an ambulance had been called to the Tuscan farmhouse at about 9.15pm on Sunday, but when paramedics called his family to clarify directions, they were told they were no longer needed as he was being taken to Rome.
Nobody has so far been named as a suspect.
Daniele, who would have been 60 in March, died of a heart attack after arriving at Saint Eugenio hospital in the capital.
A Naples native, he was famous in Italy for bringing traditional Neopolitan song to music-lovers across the country, blending it with jazz, rock and blues.