Rebekah Brooks, the embattled chief executive of Rupert Murdoch\'s British newspaper arm, quit Friday as the media baron made his biggest sacrifice yet in the phone hacking crisis rocking his empire. As an FBI investigation spread the crisis to the United States, Murdoch abandoned his very public attempts to protect his flame-haired lieutenant from attacks by politicians, and finally accepted her resignation. Murdoch had until now weathered the firestorm, closing down the shamed News of the World tabloid where Brooks was once the editor and scrapping a buy-out of British satellite broadcaster BSkyB, but refusing to sack Brooks. The 43-year-old Brooks -- dubbed Murdoch\'s \"fifth daughter\" because of her closeness to the elderly magnate -- told News International staff that she felt a \"deep sense of responsibility for the people we have hurt\". \"My desire to remain on the bridge has made me a focal point of the debate. This is now detracting attention from all our honest endeavours to fix the problems of the past,\" she wrote in an internal email. \"Therefore I have given Rupert and James Murdoch my resignation. While it has been a subject of discussion, this time my resignation has been accepted,\" wrote Brooks, whose offer to resign last week was rejected by Murdoch. Brooks was editor of Britain\'s biggest selling Sunday newspaper from 2000-2003 at the time when it allegedly hacked the phone of murdered teenager Milly Dowler, the claim that sparked the crisis. She has denied all knowledge that the practice was in use at the time. The scandal has since drawn in British Prime Minister David Cameron, politicians and the police, raising the spectre of a corrupt nexus at the heart of the British establishment. Cameron -- himself under pressure for his friendship with Brooks and his employment of her News of the World successor Andy Coulson as his former media chief -- thought her resignation was \"the right decision,\" a Downing Street spokesman said. Sky News reported that Downing Street would release details of Cameron\'s meetings with News International executives. Brooks will be replaced by New Zealander Tom Mockridge, chief executive of Murdoch-owned satellite broadcaster Sky Italia, who must now restore faith in the mogul\'s remaining British newspapers The Sun, Times and Sunday Times. Australian-born Murdoch\'s son and heir apparent, James Murdoch, announced that News International would this weekend run advertisements in all British newspapers to \"apologise to the nation for what has happened.\" Brooks\' resignation ends a meteoric rise through the ranks of Murdoch\'s empire, having started as a secretary at the News of World at the age of 20. She went on to edit The Sun, the country\'s most popular paper, until 2009. Murdoch\'s closure of the 168-year-old News of the World was seen by many observers as an attempt to save Brooks. That was reinforced on Sunday when, having been asked to name his priority, he pointed to Brooks and said: \"This one.\" It also came as a surprise, as Murdoch had only hours earlier sounded a defiant tone, breaking his silence over the scandal to insist that the crisis was being handled \"extremely well in every way possible\". In an interview with his flagship US newspaper, The Wall Street Journal, Murdoch said an independent committee led by a \"distinguished non-employee\" would probe every charge of misconduct made against News Corp. Murdoch, 80, and his son, the chairman of News International and deputy chief operating officer of News Corp., will on Tuesday be quizzed by a committee of British lawmakers, having initially resisted. Brooks will also testify. In the United States, the Federal Bureau of Investigation announced that News Corp. employees may have targeted the phone records of victims of the September 11 attacks. The FBI inquiries are preliminary in nature and do not constitute a formal investigation but US Attorney-General Eric Holder said Friday his office was reviewing requests from congressmen for a probe into News Corp. Nine people have been arrested over the scandal so far. The latest was Neil Wallis, a former deputy editor of the News of the World and one-time editor of another tabloid, the Sunday Mirror. Wallis, 60, had been deputy to Coulson at the News of the World. The scandal has also embroiled the police with the revelation that Wallis had been hired by Scotland Yard Chief Paul Stephenson, prompting calls on Friday for the commissioner to quit.