AMNA NAWAZ: The world's most powerful drug kingpin pled not guilty this morning to weapons, money laundering and drug trafficking charges.

Those drugs included cocaine, heroin and fentanyl, the synthetic opioid that killed 100,000 Americans last year alone.

Ismael Zambada Garcia, also known as El Mayo, founded the Sinaloa cartel with his imprisoned partner in crime, Joaquin "El Chapo" Guzman, and has been wanted by U.S. authorities for years.

Garcia was arrested with one of El Chapo's sons, Joaquin Guzman Lopez, at an airstrip in the United States.

For more on what their arrests will mean for the fentanyl crisis, we turn to Keegan Hamilton, criminal justice editor at The Los Angeles Times.

Keegan, welcome back.

So, before we dive into how this happened and what it all means, just tell us a little bit about these two men.

Ismael Zambada and Joaquin Guzman Lopez.

Who are they and what were their roles in the Sinaloa cartel?

KEEGAN HAMILTON, Criminal Justice Editor, The Los Angeles Times: El Mayo Zambada is one of the highest-profile drug traffickers in Mexico, sort of a legend in the drug trade in Mexico.

While other high-profile kingpins have been killed or captured over the years, El Mayo has somehow remained free and atop the Sinaloa cartel.

He's known for being a long time partner of El Chapo, and the son who was arrested alongside with him is a son who was known as a leader of another Sinaloa cartel faction known as Los Chapitos.

So these are both incredibly high-ranking, important individuals in the Sinaloa cartel, and their arrests could be pretty significant in Mexico moving forward.

AMNA NAWAZ: So as you noted there, Guzman Lopez is the son of the notorious El Chapo, helped founded the Sinaloa cartel with Zambada, or El Mayo, as he's known.

And we should note El Chapo is now serving a life sentence in a U.S. federal prison after two daring escapes from Mexican prisons.

So now he is in prison.

These two men are in custody.

How could all of these arrests - - and what would they actually mean for how much fentanyl in particular and how many drugs are making their way into the U.S.?

KEEGAN HAMILTON: I mean, the U.S. government has identified El Mayo and Los Chapitos as two of the primary suppliers of fentanyl and other drugs, including cocaine, methamphetamine, and heroin, to the United States.

So the hope is that by taking out these top leaders that the organization will sort of crumble.

However, we have seen over the years that the Sinaloa cartel is remarkably resilient.

El Chapo was captured, as you said, now serving life in prison.

The Sinaloa cartel lives on through his sons.

One of those sons now in custody, but there are several others who remained free and are still believed to be leading that faction of the cartel.

One of El Mayo's sons remains free in Mexico and is wanted by the U.S. government.

So it's not as if taking these guys out has ended the drug war overnight.

In fact, I think the business is going to continue as usual.

Their concern is, however, that when you take out a top kingpin like this, that it creates a power vacuum and that there's fighting to sort of fill that and fill their shoes.

We saw that after Chapo's capture.

And what I'm hearing so far from the state of Sinaloa is a lot of concern and fear that this is going to result in violence there.

AMNA NAWAZ: Well, tell us what we know about how they came to be in custody in the first place.

We know both men were detained at a private airport in El Paso.

A lawyer for Zambada, in particular, said his client did not voluntarily fly across the border.

So how did they end up in El Paso and how did they end up in U.S. federal custody?

KEEGAN HAMILTON: Yes, we're still figuring out the exact details of what transpired.

I did speak to El Mayo's lawyer this morning and he was adamant that his client was -- did not surrender, did not come voluntarily.

And we have heard a lot of rumors swirling right now that there was a setup, that he did surrender, and that this denial is a ruse.

What we can say for sure is that the Mexican government has released some information about it that they were able to glean, that his private airplane left the city of Hermosillo, Mexico, around 8:00 this morning and landed - - or -- excuse me -- yesterday morning, Thursday, and landed in El Paso a couple hours later.

Both of these suspects were processed.

We have seen photos of them.

They took their photo -- their fingerprints to confirm that it is in fact the people that they say they are.

So we will get more details in the coming days about how exactly they were lured here or tricked here.

But the fact that this -- El Mayo, in particular, who has been a fugitive for over four decades, is captured is a really stunning turn of events.

AMNA NAWAZ: Keegan, it's also worth noting in the minute or so I have left here that these men and this cartel have fueled mass violence in Mexico as well.

What does it say to you that these arrests were brought by U.S. authorities and not Mexican?

KEEGAN HAMILTON: Yes, it's interesting.

It appears that Mexican authorities had no role in any of this operation.

They have said so publicly and seem to be scrambling for information about what happened, just like everyone else.

The U.S. has worked hand to hand over the years with Mexico, but that relationship has become more difficult over the years.

And the fact that the U.S. is bringing these people to justice is pretty remarkable.

We will see what happens with El Mayo's case, whether he takes to trial, whether he pleads out.

We have seen other instances where these folks have pleaded guilty and cooperated and received relatively short sentences.

So we don't know what's going to play out in this case and what his punishment is going to be.

AMNA NAWAZ: That's Keegan Hamilton, criminal justice editor for The Los Angeles Times, joining us tonight.

Keegan, great to see you.

Thanks for joining us.

KEEGAN HAMILTON: Thank you.