A Mexican drug suspect awaiting trial in Chicago is making a startling claim. He insists he can't be prosecuted because he worked as an informant and had a secret immunity deal with the U.S. government.
Prosecutors say Vicente Zambada-Niebla oversaw drug running on a massive scale into the U.S. But now, from behind bars at a maximum security prison in Chicago, he's making his own explosive accusations -- that U.S. government agents have been aiding Mexico's infamous Sinaloa cartel -- even tipping off leaders on how to avoid capture.
CBS News investigative correspondent Sharyl Attkisson reports that Zambada's court filings claim federal Drug Enforcement Administration agents gave him, cartel kingpin Chapo Guzman, and other Sinaloa leaders "carte blanche" to "operate their drug business without interference," as long as they snitched on other cartels. For years, Zambada's attorney argues, Sinaloa leaders helped "authorities capture or kill thousands of rivals." Their chief rivals are the Zetas, considered the most vicious and ruthless of all.
Phil Jordan used to head the DEA's Center for Drug Trafficking Intelligence, called "EPIC," in El Paso. He says he doesn't buy Zambada's claim that the DEA promised immunity.
Jordan told CBS News, "We do not have the power to offer immunity."
But in court documents, prosecutors do admit the U.S. had a signed cooperation agreement with a different Sinaloa cartel leader.
That agreement was with Sinaloa cartel lawyer Humberto Loya-Castro. Starting as early as 2004, Loya passed information to the DEA from cartel leaders including Zambada -- the one now on trial. In return, Zambada claims, the U.S. dismissed a major case against Loya and agreed to "not ... interfere with" the cartel's "drug trafficking" or actively prosecute their leadership.
Jordan says any agreement with a cartel leader is controversial, but may be deemed necessary.
He said, "It's probably a matter of trying to get inside or closer intelligence to the whole Mexican federation, as we call it."
Jordan points out that Panamanian dictator Manuel Noriega was once on the CIA's payroll. And that in Colombia, the U.S. worked with select cartels, allowing them to continue drug smuggling operations in the U.S. as long as they helped in destroying the more dangerous Cali and Medillin cartels.
As to whether the government has similar plans in Mexico, they're not saying, but this case, Attkisson reported, raises the question.
Prosecutors say even if federal agents did promise Zambada immunity -- which they deny -- it's unenforceable.