LONDON — It was riveting theater, a newly emboldened parliamentary committee facing off against the 80-year-old Rupert Murdoch, the world’s most powerful media mogul, in a series of exchanges designed to get to the bottom of the phone hacking scandal that has engulfed not just Mr. Murdoch’s News Corporation, but also Britain’s political and law-enforcement elite.

In two hours of intense questioning broken only by a bizarre incident in which Mr. Murdoch was accosted with what appeared to be a foil pie plate filled with shaving cream, both he and his son James declared repeatedly that they had been shocked to discover something that has become increasingly apparent: that phone hacking and other illegal behavior were endemic at their News of the World tabloid, which is now defunct.

Even so, the Murdochs and Rebekah Brooks, a former editor at the paper who resigned from the News Corporation on Friday, only to be arrested on Sunday on suspicion of phone hacking and bribing the police, apologized again and again for the failures at their company.

“I would just like to say one sentence,” Rupert Murdoch said, breaking at one point into a long answer by his son, the News Corporation’s deputy chief operating officer. “This is the most humble day of my life.”