Drug Wars Coming to U.S.?

Although murder rates and other violent crime rates have been steadily dropping for the past few decades, there has been a recent uptick. My initial thoughts on the uptick was that it might be an anomaly, or due to worsening economic conditions. However, this article from USA Today puts a different prospective on it:

A spike in murders in many cities is claiming a startling number of victims with criminal records, police say, suggesting that drug and gang wars are behind the escalating violence.
Police increasingly explore criminal pasts of homicide victims as well as suspects as they search for sources of the violence, which has risen the past two years after a decade of decline, according to the FBI's annual measures of U.S. crime.

Understanding victims' pasts is critical to driving crime back down, police and crime analysts say. "If you are trying to look at prevention, you need to look at the lives of the people involved," says Mallory O'Brien, director of the Homicide Review Commission in Milwaukee.

In Baltimore, about 91% of murder victims this year had criminal records, up from 74% a decade ago, police reported.

In many cases, says Frederick Bealefeld III, Baltimore's interim police commissioner, victims' rap sheets provide critical links to potential suspects in botched drug deals or violent territorial disputes.
. . . The slaying of truly innocent victims is so unusual in Baltimore that the chief prosecutor says the city has become dangerously numb to the carnage. "If we don't put human faces on the victims, we will become desensitized," State Attorney Patricia Jessamy says.

 (Underline added). The article discusses findings from other cities, as well, supporting the same trend. The question is whether there is a link between this increase and the Mexican cartels--that is, are rivalries from south of the border moving north, or are more violent gang members coming from the cartels? Or is this an independent phenomena?