New Delhi, Sep 21 : Controversial media mogul Rupert Murdoch has resigned as chairman of Fox Corp and News Corp marking the end of an over 70-year career during which he built a business empire stretching from Australia to the US.   His older son, Lachlan Murdoch, 52, will become sole chairman of News Corp and will continue as Fox Corp's executive chair and CEO which finally settles all questions of succession within the Murdoch family. Fox said in an announcement on Thursday that Rupert Murdoch, 92, would become chairman emeritus of both companies. In a note to staff reported in the Murdoch-controlled Wall Street Journal, he wrote: "For my entire professional life, I have been engaged daily with news and ideas, and that will not change. But the time is right for me to take on different roles." "Our companies are in robust health, as am I. We have every reason to be optimistic about the coming years ' I certainly am, and plan to be here to participate in them," it added. In the note Murdoch also referred to Lachlan as a "passionate, principled leader" who can take the companies into the future. There was a split in the Murdoch family over succession after decades of wrangling, which saw his younger son James quit the business. However, his daughter Elizabeth had stayed away from the battle for succession. The Fox founder's decision to step down comes just months after his news network paid over $787.5 million to settle a defamation suit filed by voting equipment company Dominion. The company had accused Fox of knowingly broadcasting outlandish allegations that it was involved in a plot to steal the 2020 election. /IANS