Democratic presidential candidate Hillary Clinton speaks at a United Food and Commercial Workers International union Legislative and Political Affairs conference, Thursday, May 26, 2016, in Las Vegas. Clinton was supposed to have turned over all work-related emails to the State Department to be released to the public. But an agency audit found at least three emails never seen before — including Clinton's own explanation of why she wanted her emails kept private. (AP Photo/John Locher)

Origins of key Clinton emails from report are a mystery

Democratic presidential candidate Hillary Clinton has insisted she turned over all work-related emails to the State Department to be release…