Capping a day that included News Corp. Chief Executive Rupert Murdoch being attacked with a foam pie, Murdoch protege Rebekah Brooks denied authorizing payoffs to police sources and refused to blame any staff for what she acknowledged were "horrific" incidents of hacked phone and email communications to get story material.
Murdoch, for his part, told a British parliamentary committee that those responsible are "the people that I trusted to run it (The News of the World), and then maybe the people they trusted."
Brooks, who resigned last week as head of News Corp.'s British newspaper operations, in her testimony apologized for the hacking.
"I also regret the speed in which we have found out, or tried to find out the bottom of this investigation, has been too slow," she said.
Asked whether she had been lied to by senior News of the World employees during an internal investigation, Brooks declined to answer.
She denied knowing the private investigators at the heart of the hacking allegations as well as having made any police payoffs.
"I can say I have never paid a policeman myself," she added. "I've never knowingly sanctioned a payment to a police officer."
Earlier, a protester attacked Murdoch with what appeared to be a plate of shaving cream, as lawmakers grilled him and his son James.
Murdoch was answering questions when the attacker leapt from the public viewing area.
Murdoch's wife, Wendi Deng, jumped to his defense, swinging at the attacker's head.
"You are a greedy billionaire," the attacker said, according to a witness in the committee room.
Max Beckham, a politics student who was among members of the public at the hearing, told msnbc.com that as the attacker got up "he was muttering something under his breath. He was a little bit disheveled."
"His (Murdoch's) wife, Wendi, jumps up and smacks him about three, four, five times, like hard, proper blows," he added. "She was going for it. She tried her hardest to smack him really hard."
The man was taken away to be questioned by police, NBC reported. He was later identified as a left-wing comedian.
Testimony resumed after a break of about 15 minutes, and Murdoch continued to answer questions with his jacket removed before concluding and making way for Brooks, who was arrested Sunday in connection with the investigation.
Sky News identified the attacker as comedian and activist Jonnie Marbles. Before the attack, @JonnieMarbles tweeted:
Murdoch told the committee that he was not responsible for the scandal, adding that he was "shocked, appalled and ashamed" when he read the about the surveillance of a murdered teenage girl's voicemail by the now defunct News of the World newspaper.
Under questioning from lawmakers, Rupert Murdoch defended himself and his company, asserting that "The News of the World is less than 1 percent of our company. We employ 53,000 people around the world who are ethical."
He later added that he "very seldom" spoke with the editor of the News of the World although he did speak more frequently with the editor of the Sunday Times.
Murdoch also said he had seen no evidence to support another recent suggestion — that his journalists might have tried to spy on the families of victims of the 9/11 attacks in the United States. The FBI is looking into that allegation.
Murdoch appeared at times confused and often deferred to his son to answer questions about his company's actions.
Lawmaker Philip Davies asked the Murdochs what coaching they had before their appearance, and James responded that he had been advised to tell the truth.
Both Murdochs seemed from their answers to be out of touch with the day-to-day activities at the companies, with James Murdoch saying that he was shocked when he found out the company paid legal fees for a reporter found guilty of hacking. Earlier, his father denied knowledge of payments that the company made to settle lawsuits by phone hacking victims.
News International Chairman James Murdoch, 38, said they did not believe the two most senior executives to have resigned, Brooks and Les Hinton, knew of wrongdoing.
'Matter of great regret'
Sitting next to his father, James Murdoch began the proceedings before parliament's Culture, Media and Sport Committee by offering an apology for the company's actions.
"This is a matter of great regret, mine, my father’s and everyone at the News Corporation," he said. "These actions do not live up the standards our company aspires to everywhere around the world and it is our determination to put things right, to make sure these things do not happen again and to be the company that I know we have always aspired to be."
Rupert Murdoch interrupted his son's initial comments to declare: "I would just like to say one sentence. This is the most humble day of my life."
News International had long maintained that the practice of intercepting mobile phone voicemails to get stories was the work of a sole reporter on the News of the World who, along with a private investigator, were jailed for several months in 2007.
That "rogue reporter" defense crumbled under a steady drip-feed of claims by celebrities that they were targeted. James Murdoch said he acted swiftly to cooperate with police when it became clear a few months ago in dealing with civil suits over phone hacking that there was evidence of wider criminality.
The long-smoldering scandal has shaken Britons' confidence not only in the press, but also in the police and in politicians, including Prime Minister David Cameron. The Murdochs' appearance before parliament committee attracted huge amounts of attention in Britain where local newspapers ran live video of the hearings on their websites.
One lawmaker on the committee mistakenly said that journalist Piers Morgan, now host of his own show on CNN, had admitted in his recent book that he participated in the hacking.
Morgan later appeared on CNN to describe how the lawmaker had mistaken what he said in the book. "I wrote in my book that someone warned me phones could be hacked, so I changed my pin number."
Earlier Tuesday, former Metropolitan police commissioner Paul Stephenson, who resigned on Sunday, appeared before a separate parliamentary committee on allegations of police corruption linked to the phone-hacking scandal. Stephenson told the committee that 10 out of 45 press officers in the police force had previously worked for News of the World, but denied that there was an improper relationship between the two.
When questioned about Neil Wallis, the former News of the World editor employed by the Met who has since been arrested in connection with the phone-hacking investigation, Stephenson said he had had "no reason to doubt Mr. Wallis' integrity."
He said he had only found out that Wallis was a suspect in the case "several weeks ago."
Hackers target The Sun
The scandal, which the parliamentary committee has been pursing for more than four years, exploded into public view two weeks ago when a lawyer for the family of the murdered teenage schoolgirl Milly Dowler claimed the paper had hacked her phone when she was missing, deleting messages and raising false hopes she could be still alive.
The ensuing outrage prompted News Corp. to close the 168-year-old News of the World newspaper, drop a $12 billion plan to take full control of pay TV operator BSkyB, and saw the arrest of Brooks.
Murdoch-affiliated newspapers were themselves the target of hackers on Monday.
LulzSec, the group of hackers that said three weeks ago it was disbanding, claimed credit for defacing The Sun newspaper website, while an allied group, Anonymous, claimed credit for a denial-of-service attack that brought down the website of The Times. The Sunday Times and News International sites also appeared to be down Monday.
Questions for Cameron
Cameron, who took office in May 2010, cut short a trade trip to Africa and was due to return late on Tuesday to attend an emergency debate the following day in parliament, which is delaying its summer recess.
He is facing the worst crisis of his premiership as his decision to appoint former News of the World editor Andy Coulson as his communications chief is questioned. Coulson quit as News of the World editor in 2007 when the paper's royal reporter was jailed for phone hacking. Coulson said he knew nothing of the practice but took responsibility.
He quit as Cameron's spokesman in January when the long-running scandal came back to life. He was arrested earlier this month and is also free on bail.
Cameron's position has been made worse by a parting shot from Stephenson, brought low by the force's decision to hire a former News of the World deputy editor now implicated in the scandal as a media adviser.
In his resignation statement, Stephenson appeared to be contrasting his behavior with that of Cameron, who employed former News of the World tabloid editor Andy Coulson as his communications chief.
However, facing a parliamentary committee on Tuesday, Stephenson said he had meant no criticism at all of the prime minister.
Few expect the prime minister to quit but he appears weakened as head of a deficit-cutting coalition and might find his room for maneuver limited.