NYPD officer shootings: What do we know

U.S. Attorney General Eric Holder called the slayings of two NYPD officers an “assassination.” Both President Obama and New York City May Bill de Blasio condemned the killings in no uncertain terms. But all three officials came under fire this weekend from critics who accuse them, in one way or another, of creating a climate that placed police officers in jeopardy and ultimately, cost two their lives. But aside for the rhetoric and war words between both sides of the debate, how did we get here? CNN's Martin Savidge reports.