It's not "Both Sides Do It."

The sheriff from Pima County, Arizona, made some generic comments about the number of threats that public officials are receiving recently.  He said that is making his job of keeping the peace more difficult.  He did not single out any one instance or group.  Liberals, as best I can tell, have more or less nodded sagely.  Conservative politicians and commentators are criticizing him for bringing politics into this tragedy.

First off, let me just say that when someone plans and executes an assassination attempt on a politician, by definition, that is political.

Second, the only people I see complaining about the comments are conservatives.  GOP members and their supporters.  The rhetoric of political right is infused with militarism and the encouragement of violence.  One has to suspect, at some point, some one is going to act on these suggestions.  This violent rhetoric is extremely rare on the political left in the U.S.  Right around the 2008 election remember a conservative leaning friend of mine making a statement to the effect that if Democrats over reach there will be a political assassination attempt.  It was just a "logical" conclusion to reach.   Folks, Sen. Jon Kyl's and  Rep. Trent Franks' statements, Sarah Palin removing the Cross Hairs ad, these are actions associated with a classic case of a guilty conscience. 

This is clear cut.  Liberals do NOT regularly issue threats of violence towards their political rivals. 
Conservatives and their "Second Amendment remedies" to losing elections regularly push violence.