News Corp. CEO Rupert Murdoch pauses as he delivers a keynote address at the National Summit on Education Reform on October 14, 2011 in San Francisco, Calif. Murdoch told a U.K. government inquiry today he didn’t know about phone hacking at one of his British newspapers. U.S. investigators are watching closely. - 

Tess Vigeland: Media mogul Rupert Murdoch testified again today in a British government investigation into media ethics and standards. He admitted there'd been a cover-up of wrongdoing at one of his British newspapers, The News of the World. He's now shut down that paper.

And today, he said he'd been kept in the dark about the extent of illegal activity there. From London, Marketplace's Stephen Beard reports.

Stephen Beard: He’s the world’s most powerful media magnate, once courted and feared by politicians on both sides of the pond. But today, a different Rupert Murdoch appeared before the ethics enquiry. Contrite and humble, he apologized profusely for the phone hacking at the News of the World.

Rupert Murdoch: I failed. All I can do is apologize to a lot of people including all the innocent people on the News of the World who lost their jobs.

But he said the scale of the illegality had been concealed from him.

Andrew Neil is a former Murdoch executive. He says that in his two days of testimony, his old boss has carefully dodged any suggestion that he was complicit in the malpractice.

Andrew Neil: He’s been hosed down by his American lawyers who’ve told him not to say anything which could cause trouble in America where he’s under investigation by the Department of Justice, the SEC and the FBI.

They are reportedly looking at allegations that Murdoch’s British journalists bribed police officers. That would be illegal under the U.S. Foreign and Corrupt Practices Act.

And then, says Jeff Cohen, professor of journalism at Ithaca College in New York, there's the issue of phone hacking.

Jeff Cohen: If there’s phone hacking that’s discovered on U.S. soil , that opens up new problems for Rupert Murdoch that he hasn’t even fathomed yet.

Civil lawsuits and criminal prosecutions in the U.S., and says Cohen, perhaps Congressional hearings too. Murdoch may need all the contrition he can muster.

In London, I’m Stephen Beard for Marketplace.