The News of the World's ex-legal manager said that he told James Murdoch there was "direct and hard evidence" that phone hacking extended beyond a single reporter.
Tom Crone said he showed the News International chairman a printout of the now-notorious "For Neville" email, which apparently contradicted the corporation's previous stance that phone hacking at the paper was confined to a single "rogue reporter".
The email, which contained transcripts of illegally intercepted voicemail messages, was apparently destined for the News of the World's chief reporter Neville Thurlbeck.
Mr Crone told the Leveson Inquiry into press standards he showed Mr Murdoch a number of documents at a meeting in June 2008.
"I cannot remember whether they were passed across the table to him, but I am pretty sure I held up the front page of the email," he said.
"I am also pretty sure that he already knew about it - in terms of it had been described to him already, which I think the other documents that have come out suggest anyway."
He added: "What was certainly discussed was the email - not described as For Neville, but the damning email - and what it meant in terms of further involvement in phone hacking beyond Goodman and Mulcaire.
"And what was relayed to Mr Murdoch was that this document clearly was direct and hard evidence of that being the case."
Clive Goodman, the News of the World's former royal editor, was jailed along with private investigator Glenn Mulcaire in January 2007 after they admitted intercepting voicemail messages left on royal aides' phones.
Mr Murdoch has insisted that he was not shown the email or told that it proved phone hacking was more widespread at the News of the World than previously thought.