Police forensic experts returned to Olsen's downtown studio on Wednesday morning, a day after it emerged that the 35-year-old had been strangled to death, most likely by someone she knew.
Olsen's naked corpse was found at the flat on Saturday afternoon. She had last been seen by friends at a nearby nightclub in the early hours of Friday.
A postmortem examination indicated that Olsen, an artist and event organizer who had lived in Florence for several years, had been strangled with some kind of cord or cable but revealed no sign of her having put up a struggle.
According to broadcaster Rai and daily La Repubblica, the autopsy also established that Olsen had recently had sex, while witness statements and CCTV footage indicate that she had met up with an unidentified man after leaving the nightclub shortly before dawn.
The man is now considered as the primary suspect in the murder investigation with police considering two theories about how Olsen died, the news outlets said.
Either it was the result of an erotic asphyxiation game which went wrong or she was strangled while in a semi-comatose state and unable to resist.
The prosecutor in charge of the case has refused to comment on whether any drugs were found in the studio apartment.
The Montecarla nightclub visited by Olsen in the early hours of Friday has been temporarily closed down several times in recent years, most often because of concerns it was being used by dealers to sell drugs.