The IPCC said the three arrested were a 50-year-old sergeant who was arrested at work, a 29-year-old Pc arrested at an address in south London and a retired PC aged 48 who was arrested by appointment at a central London police station.
Sean Rigg died from a cardiac arrest at Brixton police station in August 2008 and the inquest jury found that police officers used "unsuitable" force after arresting the 40-year-old schizophrenic for attacking passers-by and police officers in Balham, south London.
More top news
The alleged hacking follows reports of similar attacks on other Democratic organisations, amid fears of state-sponsored hacking.
One lucky ticket holder based in the UK has won a cool £61 million jackpot in the EuroMillions lottery game.
A crowdfunding campaign has been set up to raise money needed for a legal battle to bring home Michael Sandford.