[circlecity]

"A study released last year by the city found that almost 60 percent of firearms recovered at Chicago crime scenes were first bought in states that do not require background checks for Internet or gun show sales, like neighboring Indiana and Wisconsin. Of the remaining crime guns, nearly half were purchased at three gun shops just outside the city."

This statement is quite misleading. Regardless, of where the guns were purchased the overwhelming majority were stolen by either the shooter or someone else who illegally sold it to the shooter. I also note that the places with these supposedly "lax gun laws" don't have near the shooting that Chicago has, so it's not the laws of these states that is the problem.

[TigersEye]

...states that do not require background checks for Internet ...

The only way you can buy a gun on the internet without a background check is to buy it from someone like Trayvon Martin.

It's a Federal law that covers all states that all sales through licensed dealers must conduct a NICS background check.