It's moving pretty fast for any typical and complicated LE investigation.
Arpaio didn't start his investigation since what mid to late 2011 when the local Tea Party petitioned him to look into the matter of the fake OBama White House birf certificate. Sheriff Arapio's first presser came a short time later in March 1, 2012 and the next one in July.
The big breakthrough in the case came in or about in the month of October, 2013, and that wasn't publicly mentioned until November 7, 2013 as reported here.
Breakthrough in Birth Certificate Case (Nov 7 2013)
Let them flap their fly traps, people are taking notes.