From Halopedia, the Halo wiki
Josh Keegan was a human who listened to Benjamin Giraud's Hunt the Truth audio journal in 2558. After Giraud's entries revealed witnesses from all over the colonies with different stories about the Master Chief, Keegan mailed Giraud an audio email where he expressed his skepticism. Having grown up on Earth, Keegan felt a UNSC coverup would be much too difficult for them, and viewed the Outer colonists as merely panicking over random theories. He suggested that Giraud ignore them and get some rest.
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