One gun sold outside Louisville in December 2016 was used just four months later in an armed carjacking in west suburban Westchester, according to the complaint. Another, purchased in May 2017, was found within three months on a man arrested for pointing the gun at someone during a verbal altercation on the street. Other weapons tied to the trafficking scheme quickly turned up during narcotics investigations, court-authorized searches or hidden under car seats during traffic stops, according to the charges.