Murdoch was testifying on Tuesday at Lord Justice Brian Leveson's inquiry into media ethics to answer questions about his role in the phone hacking scandal at Rupert Murdoch's now-defunct News of the World tabloid.
The 39-year-old Murdoch said he had no reason to doubt his subordinates when he took over at News International, which published the News of the World, in 2008. "I do recall receiving assurances around journalistic ethics, codes of practice on a number of occasions," he told Leveson.
Murdoch repeated earlier claims that his lieutenants had misled him about the scope of the illegal behaviour in the News of the World's newsroom.
"I was given assurances by them, which proved to be wrong," he said.
Revelations that reporters at the News of the World had hacked into the phone of a teenage murder victim led Murdoch's father Rupert to close the 168-year-old newspaper and triggered three UK police investigations, more than 100 lawsuits, and Leveson's inquiry into media practices.
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Murdoch has found himself sucked into the centre of scandal, with critics saying that he should have found out about the wrongdoing once he took over.
Murdoch stepped down as chairman of News International in February and resigned from his post as chairman of British Sky Broadcasting Group PLC earlier this month - moves seen by many as efforts to distance himself from the scandal. He told Leveson that he left his position at BSkyB because "I wanted to avoid being a lightning rod".
Rupert Murdoch, who is still chairman and chief executive of News International's parent company News Corp, will appear before the inquiry on Wednesday.
