The federal agents who visited Scott Taylor’s rural Pennsylvania gun shop in early January 2010 — to conduct the store’s first inspection in more than three decades — found thousands of violations of firearm sales laws.

Taylor couldn’t properly account for more than 3,000 guns he had bought or sold during the previous three years, according to agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives. These and other violations led ATF to revoke his license to sell guns in November 2011. But that wasn’t the end of the story. Far from it.