The FBI is investigating reports that Rupert Murdoch's News Corporation sought to hack the phones of victims of the 9/11 attacks, BBC reported.
The criminal probe follows calls from a growing number of senators and a senior Republican for an investigation.
In an interview with the Wall Street Journal, Mr Murdoch defended the company's handling of the crisis.
Meanwhile, Mr Murdoch and his son James have agreed to answer UK MPs' questions on the hacking scandal next week.
The Commons media committee issued summonses after the pair initially declined to appear.