(CNN) - Last year, thousands of people trying to buy guns from dealers made false statements about their past on the required federal form, then went on to fail the background check due to a serious criminal record or other disqualifier. Lying to a licensed gun dealer is a felony punishable by a fine or up to 10 years [1]in prison.

Breaking that law might seem risky. But in September, a Government Accountability Office study[2] made it clear why those who "lie and try" would take their chances. Regional offices at the Bureau of Alcohol, Tobacco, Firearms and Explosives received 12,710 cases of firearm background check denials for further investigation in fiscal year 2017, the GAO found, but the government prosecuted only 12 people. More than 99.9% of those who were investigated escaped with nothing more than a warning.

Past and present ATF agents and prosecutors told CNN that, given limited resources, they're not inclined to prioritize the nonviolent crime of lying on a form over more serious charges, like gun trafficking. The very few "lie and try" cases they prosecute focus on dangerous "trigger pullers" who clearly know they're prohibited from owning a firearm -- career criminals with a history of violence or activity in the drug trade.

But a 2006 internal ATF briefing paper obtained by CNN suggests that gun form liars are far more likely to go on to commit a gun crime than even many experts recognize. When ATF analyzed firearm denial cases sent to field offices for investigation during a seven-year period, it found that 10%-21% of that group went on to be arrested for a crime involving guns.

Take John Zawahri, who tried to buy

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