The investigation began in June and is ongoing, Booth said.
Both he and Denver District Attorney Beth McCann declined to release further details, although McCann said pending charges would be filed in state court under Colorado's Organized Crime Control Act, a law used to prosecute criminal conspiracy enterprises.
McCann left open the possibility that federal charges could be filed.
Booth insisted there was no danger to the public even as he and McCann withheld information on what McCann called "very serious" cases.
"We think it will be a safer community, a safer Denver, a safer metro area," Booth said.