Ismael Zambada Garcia was El Chapo’s right hand man for decades; co-founder of the bloodthirsty Sinaloa cartel and now he’s on the verge of pleading guilty.

Zambada’s nickname is El Mayo. But he’s about to get a new nickname…the eight numbers of his federal prison ID.  

“I think it means that like if you’re one of the major leaders of these cartels, that you’re vulnerable and you can be held accountable,” says Mike Gannon, a retired official with the Drug Enforcement Administration/Chicago Division.

Gannon tells NBC Chicago that the end of the road for El Mayo can’t be overstated.

It’s a road that starts in Sinaloa, Mexico, where El Mayo and El Chapo were partners in crime for more than four decades.

But their main illicit drug outpost was a burgeoning business in our backyard.

“Chicago is the number one drug distribution point for narcotics in the United States of America,” says Andrew Boutros, the new U.S. Attorney in Chicago and the highest ranking federal law enforcement official in the city. “Chicago is the corporate headquarters for the Sinaloa Cartel.”

There is a simple explanation for why the cartel established a beachhead in Chicago.

“Well, listen, when you look at what is happening in the Chicago area, you know that there’s so many distribution routes that come out of Chicago and to get drugs to other parts of the country, it’s a great location,” says Gannon, who formerly was assistant special-agent-in-charge of the DEA office in Indianapolis, which falls under the Chicago Division.

Chicago’s status as a drug HQ for Sinaloa has also made the cartel a major target of top federal prosecutor Boutros. In an exclusive interview with NBC Chicago, Boutros said that it’s paramount to zero in on Sinaloa cartel figures who are taking over for El Chapo and El Mayo.

Drug cartel violence that radiates from Mexico doesn’t account for all the violent crime in Chicago, but does influence and inflate the violent crime stats here.

“It doesn’t feed all of it, or, I don’t know if it feeds most of it, but it certainly contributes to it,” says Boutros.

So with drug lord El Chapo locked up at the Supermax prison in Colorado, and with his chum El Mayo headed that direction, both leaders of Chicago’s most prolific cartel are off the streets…and locked up for life. Gannon says that sends a strong message to the people who matter most: the millions of drug overdose victims over the decades as a result of cartel greed.

“When I think of the significance of both of those individuals being arrested and held accountable and, and pleading guilty, it’s huge because they got all the families that have been impacted in the United States and specifically the Chicago area as well,” he says.

In a late court filing Tuesday, Mew York prosecutors say they are planning to lump all the similar cases against El Mayo into one guilty plea…but not the indictment he faces in Chicago. That case remains in place according to the U.S. attorney here, although with EL Mayo now 77 years old, it may never need to be prosecuted