On this map, created by local data hound Ellen Worthing, the red dots represent vacant properties and each of the green dots represents one of the 126 murders that has taken place in the city this year.
While the map certainly doesn't paint anything like a complete picture of the many factors that contribute to Baltimore's murder epidemic, it does seem to show a stark correlation between empty properties and murder. Common sense tells you that the fewer "eyes on the street," as Jane Jacobs describes the stoop-sitters, window-watchers, and others who keep tabs on a neighborhood in her urban-studies classic The Death and Life of Great American Cities, the more likely people are to misbehave.
The map certainly seems to underline the importance of turning around the city's vacant properties, as the mayor's Vacants to Value program aims to do. But as the profusion of red on the map indicates, that will be an uphill battle.
Examine the map in detail at a.tiles.mapbox.com/v3/cham101.map-qcoz7gqn/page.html#12.00/39.3110/-76.6105