Italian police investigating the strangling of an American woman are examining her computer and a bra found nearby her Florence home for clues to the killer. The naked body of Ashley Olsen, 35, was found in her flat with scratches and bruises to the neck on 9 January by her boyfriend.

The man, 42-year-old Federico Fiorentini, has been questioned by police but is not being treated as a suspect, Italian media reported. Witnesses confirmed the local painter was elsewhere when the killing took place, although the exact time of death is yet to be pinpointed by the results of autopsy due later this week.

Fiorentini went to Olsen's apartment in the picturesque Santo Spirito neighbourhood just off the famous Ponte Vecchio Bridge after growing worried not having heard from her over a few days. He is understood to have told police the two had quarelled three days earlier and she had not been returning his calls since.

He let himself in borrowing a key from the landlord. Fiorentini injured his hands slightly while moving the body in an attempt to revive the woman and first called an ambulance that in turn alerted police after arriving at the scene.

Detectives believe Olsen, from of Summer Haven, Florida, knew her killer as there was no evidence the flat's front door was forced. Her body reportedly had signs of struggle, suggesting she had tried to defend herself, although investigators have not ruled out the possibility of a sex game gone wrong. The killing was witnessed by her beloved dog, Scout, a beagle, which was found alive inside the flat.

On 11 January police retrieved a black bra left on a bicycle parked less than 20 metres form Olsen's flat. It was not immediately clear if the garment belonged to the victim but forensics acquired it as evidence. Authorities are also examining Olsen's computer and security cameras from nearby streets.

The woman was last seen alive at the Montecarla cocktail bar not far from her home. She had moved from the US to Tuscany, where her father worked as a professor, a few years ago. Local media described her as a lively person who enjoyed Florence's nightlife.

"I can't imagine a person who would hurt her. She is a gentle, a kind, a beautiful, friendly, lovely girl and it's an awful shock," Amy, a friend who only gave her first name, told AP. "We've got a great community here of people and everyone loved her."

Olsen's active social media presence has also drawn the attention of investigators. In a couple of Instagram postings from September 2015 she appeared to complain of a stalker.

"I have #stalker #stalkeralert #creeperintheback #creeperpic," she wrote as caption to a photo of her walking her dog. However police said she never reported the matter to them and it was not clear if the postings had been serious or light-hearted, Ansa news agency reported.

Meanwhile authorities pledged to deal with the case with "maximum attention". A murder investigation has been opened. "What happened in Florence is getting the maximum attention to find out what it's all about," said Italy's police chief, Alessandro Pansa.