Arlington police chief Doug Scott is crowing, but maybe has his fingers crossed, too. The county has not had a homicide in two years, since a murder by stabbing in March 2009. He doesn't want to jinx the good run by making too much noise, but he acknowledges it's a combination of luck, good police work, and the urban advantages of EMT and trauma hospitals in close proximity.

"Sometimes when you have somebody with a gunshot or stab wound it could be the matter of a quarter of an inch one way or another and what was categorized as an aggravated assault could have been a homicide," he says. That's luck. "But I wouldn't discount good police work, great visibility in the community, and tremendous partnership with our community." Also, he points out, "we have a great fire department and multiple trauma centers." The EMTs work within the fire department.

He says the success rate is not due to having too many police. Arlington County has an "authorized strength" of 360 officers, which equates to 1.6 officers per thousand residents. "That's pretty light, considering," he says.

Scott says a "fairly significant" number of the individuals arrested have residency in DC or elsewhere outside of Arlington. The assault crimes, he explains, break down generally as domestic, between two juveniles, gang-related, and in and around Metro stations.