The FBI Can Find These E-Mails But Not The IRS's?

From the NY Daily News: The FBI has seized 80,000 potentially damning emails from Rupert Murdoch’s News Corp., giving the media titan worries on both sides of the Atlantic in the ongoing phone hacking scandal.
While Murdoch was in London on Thursday facing the fallout from the conviction of one of his former star editors, it was disclosed in the U.S. that the FBI took and shared the mountain of emails with British prosecutors.
The emails, all copied from servers at News Corp.’s Midtown headquarters, include messages Rebekah Brooks, Murdoch’s former protégé, sent up the chain of command during the height of the phone-hacking scandal, The Daily Beast reported.
The emails have been shared with British prosecutors, but they were not used as evidence in the trial of Brooks and former News of the World editor Andy Coulson.
It was not immediately clear what the emails say or what the FBI further intends to do with them.   http://www.nydailynews.com/news/world/rebekah-brooks-feels-vindicated-acquittal-article-1.1845169
Strange they would find the e-mails from the owner of Fox News  but they cannot find the e-mails from the IRS.