RR was recommended by others in the DOJ to replace insubordinate Yates.
The President was still very new on the job with leakers and devices everywhere.
[Sessions] picked someone who grew up in the department and knows how cases are decided, and should be decided.
Jamie Gorelick, deputy attorney general from 1994-1997
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AFTER THE FACT Rosenstein's memo gives Mueller a more specific description of his authority:
it specifically states that Mueller has the authority to investigate Paul Manafort
for any crimes arising out of payments he received from the Ukrainian govt before and during President Viktor Yanukovych's tenure.
And thats pretty much what Mueller indicted Manafort for.
<><> Even though Manafort's activities preceded, and had nothing whatsoever to do with, Trump's campaign.
<><> Rosenstein wrote the memo six days AFTER Mueller ordered the armed raid Manafort's house in the dead of night.