Carmine Gallo, a former top police officer and CEO of the investigative agency Equalize, has died at 66 from a heart attack while under house arrest.

Gallo was a central figure in the Milanese investigation into illegal data hacking and espionage, which targeted high-profile politicians and business leaders.

Equalize allegedly accessed sensitive state databases and spied on over 800,000 individuals, with operations extending to London and involving foreign intelligence agents.

Gallo, once a celebrated crime fighter, had a long career tackling organized crime before transitioning to private investigations.

His death is a significant setback for prosecutors, as he was considered the mastermind behind the network.

The investigation continues, with other suspects still in custody.