Federal investigators said Rogelio Castaneda sold nine guns and 28 "switch" devices to undercover agents.
A recent analysis by the ABC7 I-team found a significant jump in arrests in Chicago, linked to guns modified with switches.
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The city of Chicago referenced that I-Team report in a lawsuit filed against Glock. The lawsuit says the gun-maker's pistols are too easily converted to be fully automatic.
READ MORE | Chicago area shootings made more dangerous by cheap, easy to buy 'gun switches'