So what caused crime rates to go up in 2012 in Chicago?: An extended discussion on the Dennis Miller Radio Show
The first round: On Wednesday, May 14th, an individual who identified himself as a cop from Chicago called into the Dennis Miller Show during the first hour and indicated that he strongly disagreed with one of the points that John Lott had raised on Dennis' show on Wednesday, May 7th, 2:06 to 2:30 PM, audio here.
Some facts: John Lott has written up some discussions on the changes in Chicago's crime rate here (most importantly) and here. There is also a useful article on the city producing fraudulent crime statistics available here.