TAMPA - When a gun is recovered during a police search or after the commission of a crime, investigators across America depend on the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to help them document the weapon's history. In Florida, the ATF traced 18,714 guns that were recovered by law enforcement investigators in 2009, the latest year for which such data are available. The ATF research is done at the bureau's National Tracing Center in Martinsburg,... (GunPolicy.org)