Creazzo said the man, named as Diaw Cheik Tidianee, had met the 35-year-old Olsen in a local nightclub and that the two had consensual sex in her home under the influence of alcohol, and possibly drugs, before he killed her.

She was strangled in the early hours of Friday, Creazzo said, but the autopsy revealed that she had two fractures to her skull — injuries that would also have proved fatal.

The case has attracted huge international media attention and investigators were keen to avoid any repeat of the drawn-out saga that followed the 2007 killing of British student Meredith Kercher in Perugia, not far from Florence.