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Input: The department's narcotics division began the investigation when a source told them about the group  officials said. The buys were conducted by undercover officers who infiltrated the group  according to Anthony Riccio  chief of the department's organized crime division.
 Riccio  said there are “dozens and dozens of these secret groups  a lot of them used for illegal things  including trafficking the guns and firearms. It's dozens of them out there.”
 He  said many of the guns had defaced serial numbers  making them difficult to trace. “These are guns that are winding up in the South Side  West Side of the city being used in gang shootings ”  Riccio  said.
 He  said the Facebook group selling guns and drugs would not be found by searching and that someone had to vouch for anyone who wanted to join them.
“I absolutely think Facebook has a responsibility to monitor this and for this very reason ”  Riccio  said. “There’s other illegal activities — I want to point out this is phase one — there's other illegal activities going on on Facebook. We're looking at potentially human trafficking  things of that nature as well. There's a lot of tentacles going out here.

Chicago police say Facebook did not cooperate in drug and gun