Police told The Local that two men and a woman had been arrested close to where the man was found after he fell several metres from the window of a flat in Homerton, in east London.
While the man was not named by police, he is reported to be 35-year-old Fabio Cabitza, who opened a restaurant in London after moving there from Gonnosfanadiga in Sardinia several years ago.
He was found at 3am by passersby, who called an ambulance but he was declared dead soon after.
The death of the man was initially thought to have been a result of a robbery that went wrong but police said inquiries were continuing.
Police said a post-mortem was being conducted to determine the cause of death and have appealed for witnesses.
Cabitza worked as a waiter in London before opening an Italian restaurant and pizzeria called Goppa' with a partner in Homerton.