Prime Minister Giuseppe Conte is being questioned by prosecutors from northern Italy after relatives of Covid-19 victims demanded an inquiry into alleged government negligence.
The prosecutors have travelled to Rome from Bergamo, the city near Milan worst hit by coronavirus before the whole country was locked down in March.
Mr Conte said he was "not at all worried" about the questioning.
Relatives argue that virus hotspots should have been isolated earlier.
Fifty legal complaints have been filed at the Bergamo prosecutor's office by a citizens' group called Noi Denunceremo (We Will Report).
The group consists of bereaved relatives of Covid-19 victims, who say two Lombardy towns - Alzano and Nembro - should have been declared "red zones" as soon as the outbreaks were detected there.
It is the first legal group action in Italy triggered by the pandemic. But the Lombardy region is governed by the right-wing opposition League party, and many have blamed them, rather than the central government, for alleged failures in the coronavirus response.
In addition, the prosecutors will question Italian Interior Minister Luciana Lamorgese and Health Minister Roberto Speranza on Friday.
The prosecutors aim to determine if there are grounds for any charges of criminal negligence, and whether the decision on a lockdown should have been taken by politicians in Rome or Lombardy.
Lombardy was where the virus first started spreading in Europe and more than half the victims in Italy died in the region.
On Thursday, Italy's official coronavirus death toll stood at 34,114 - the second highest figure in Europe after the UK, and fourth-highest in the world.
But Italy's infection rate has been brought down, enabling the authorities to gradually ease draconian restrictions.