Three Pittsburgh, Pennsylvania, police officers were killed on Saturday, and according to prominent left-wing bloggers including the Atlantic's Andrew Sullivan and Markos Moulitsas of Daily Kos, it's because of conservative talk show hosts on radio and television.
Most frequently named as the culprit in such vitriolic postings was Fox News's Glenn Beck.
Such a disgusting conclusion stems from comments made to the press by friends of assailant Richard Poplawski as to why he might have carried out such a heinous act.
As the Associated Press reported Saturday:

CNN practiced a more subtle form of bias during two reports in October by using its on-screen graphics. On October 14th's Newsroom program, a graphic accompanying a segment on Sarah and Todd Palin's connections to the Alaskan Independence Party proclaimed “The Palins and the Fringe.” On the other hand, a chyron from a report on Tuesday's Situation Room about Barack Obama making campaign stops in bad weather raved, “Braving Rain & Attacks: Obama in PA. and Virginia.”