Most guns recovered in Chicago were originally purchased in Illinois, not states with less-restrictive gun laws, the Chicago Sun-Times reports.
Citing a groundbreaking study at the University of Chicago Crime Lab, authorities said 58% of the 1,375 guns recovered in crimes in Chicago were bought in Illinois.
About 45% came from Cook County.
The study was requested by the Chicago Police Department because of an unusually violent 2012 when homicides spiked 28% compared to this time last year, according to the Sun-Times.
Since more than half of the guns come originate from within Illinois, authorities plan to target local gun stores that are selling the firearms.