Who is Magistrate Judge Marianne Bowler and why did she interfere in the Dzhokhar Tsarnaev investigation?

First of all, Jon Stewart's and the left's dishonest and disingenuous preening aside, you do not violate a detained person's rights by not immediately reading them their Miranda "rights."  It is allowed under federal rules.  There is also a 48 hour exception for public safety/emergency.  And all it means is the actual admissions (such as "I did it") may not be used against the detained suspect at trial (whether they are admissible or not would depend on context).  Nevertheless, the questioning itself is not a violation of Dzhokhar Tsarnaev's civil rights.

And I agree that Dzhokhar Tsarnaev, as an American citizens captured on American soil should be tried as Tim McVeigh, the Unibomber, and the Blind Sheikh were tried.  I support not designating him as an enemy combatant (had the brother Tamerlan survived being run over by Dzhokhar, I might have thought differently for Tamerlan because he was not a U.S. Citizen).  That said, I would have given the FBI the lee way of a 48 hour interrogation (given the potential danger to the public if there are others involved in this crime).

Did Magistrate Marianne Bowler do the right thing?  

Which raises the question, who sent Marianne Bowler to go Mirandize Dzhokhar Tsarnaev?  Magistrate Bowler does not work for Eric Holder or the Department of Justice.  She is an appointed federal magistrate (a junior judge in the federal system, not a confirmed Article III judge).  Did she act on her own volition or was there something more?  That is unclear.

Marianne Bowler is a Democrat appointee (politics definitely play a roll with federal judicial appointees).  Was this something set up by Eric Holder (undermining the FBI investigation in a manner that is not immediately traceable to him)?  Because given that the Russians repeatedly warned us about Tamerlan Tsarnaev (and nothing was done), is there something that Eric Holder does not want us to know?  There are a lot of questions on why more was not done to investigate Tsarnaev before this bombing took place.