2. ILLEGAL MARKET The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) issued a report in 2000 detailing firearms trafficking investigations involving more than 84,000 diverted firearms, finding that federally licensed firearms dealers were associated with the largest number of trafficked guns – over 40,000 – and concluded that the dealers' "access to large numbers of firearms makes them a particular threat to public safety when they fail to comply with the law."

3. LEGAL PURCHASES Lawful gun owners commit less than a fifth of all gun crimes, according to an analysis by the University of Pittsburgh. Epidemiologist Anthony Fabio of Pittsburgh's Graduate School of Public Health and researchers partnered with the Pittsburgh Bureau of Police to trace the origins of all 893 firearms that police recovered from crime scenes in the year 2008, The Washington Post reported.