Federal weapons experts are working with police departments across the country who suspect a link between shootings in their communities and the two sniper suspects.
Since the October 24th arrests of sniper suspects John Allen Muhammad and John Lee Malvo, the investigation has shifted to building a strong legal case for prosecutors.
That includes amassing ballistics and other evidence.
Police also began checking unsolved murders around the nation for ties to the three-week wave of sniper attacks that terrorized the Washington area.
The ATF says it is willing to work with any jurisdition that has ballistics evidence its believes may be related to the sniper investigation in the Washington region.
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