Tiller Russell couldn’t have been thrilled when he first saw the cassette of Hector Berrellez accepting an accommodation from the Federal Bar Association, a crucial turning point in his new miniseries “The Last Narc” when the tape’s wear and tear had made it practically unwatchable.

“When something like that comes in over the transom after years of chasing it and we first look at the tape and it’s like, “God, this VHS looks terrible, we can’t use it,” says Russell, who had seen his fair share of warped things in getting to the bottom of one of the ugliest chapters of the Mexican drug war. “And my instinct is, ‘No, hell yes, we can use it. We’re putting it in exactly like that.’”

After all, Russell knew it wouldn’t be enough for Berrellez to simply describe in words the topsy-turvy world he was about to enter when the medal of honor from the Bar Association led to his promotion to Chief of the DEA Pacific Division, meaning that he would soon oversee the investigation into the kidnapping and murder of Enrique “Kiki” Camarena, an undercover DEA agent in Guadalajara who had been tracking the cartels. Instituting surveillance that ultimately led to the destruction of Rancho Buffalo, Rafael Caro Quintero’s marijuana field that had become the biggest crop of its kind in the world, Camarena had one very specific enemy, but no obvious suspects in who carried out his kidnapping, leading Berrellez to figure out what the U.S. could not when they took the unprecedented step of shutting down the U.S. border in 1985 following his disappearance and while the decorated agent couldn’t know what was in store for him, the increasingly foggy tracking on the VHS gives some idea.

It’s a stylistic flourish that has become one of the ways in which Russell has taken true crime stories to another level since first tracking the corrupt cops in the sordid NYPD tale “The Seven Five” and later uncovering the crazy story of Ludwig “Tarzan” Fainberg, a Miami-based strip club owner who attempted to broker the sale of a Russian submarine to the Cali drug cartel in “Operation Odessa.” Russell has long kept the circle of people he interviews on camera small, which has been to his films’ benefit when it gives such memorable characters more time to talk, but his work has become more ambitious as his first miniseries for Amazon attests to, with Berrellez breaking his silence on his investigation of Camarena’s disappearance and once again taking audiences inside a situation where the line between opposite sides of the law was commonly blurred, particularly when the CIA’s establishment of a secret police force in Mexico known as the DFS involved many members who would come to work for the Narcos.

“The Last Narc” finds Russell talking to those who had a hand in Camarena’s kidnapping and those involved in the response to it, from Berrellez and lead prosecutor Manny Medrano, to chart a crime that rippled from the streets to the very highest echelons of power, and with the miniseries now available to stream, he spilled a few secrets of his own about how he could get to places in his own inquiry that had eluded those before, bringing his subjects to the screen with all of their personality intact and what twist in the story made him do the biggest double take.

What got you into this latest batch of craziness?

This story came to my attention via a journalist who was a mentor of mine named Charles Bowden, who took me under his wing early on in his career. It was the last great story that he was working on until his death and he died before he could complete the reporting on it. Fifteen years ago, he introduced me to Hector and told me, “This is the most important story in the history of the drug war. Watch this guy.”

So I cultivated a friendship and relationship with Hector and I’ve spent the better part of 15 years getting to know him as a human being and as a Narc and a guy that’s lived through some pretty intense trauma. So I do what I always do, which is to sit quietly and listen for as long as I can and then the architecture for what the story wants to be will reveal itself if you’re patient enough and then I waited until I had an amazing support system in the way of having producers who would fully back the vision for it and a platform like Amazon that would put it out there in a major way without asking for any compromises and just say follow the truth where it goes.

Did this story immediately lend itself to a series format or change how you went about laying things out?

Going into these things, you never know what the perfect format for it is going to be. You have the kernel of the idea, the instinct for where the story’s going to go and the vision for how it might look and feel, and the deeper that I got into the story, I saw the vast complexity of it. I wanted to do something that was a blood-soaked epic that really took it from the earliest days of the war on drugs to the most vital, explosive and controversial story at the center of it, so once we, as a team, collectively cracked that, “Okay, this needs to be epic in scope,” a “Deer Hunter” for documentaries, that lent itself naturally to the multi-part docuseries format because audiences are really watching these things right now and you’re able to get the nuance of television and yet and closed and full dramatic arc like you get in a movie.

You’ve been moving in this direction for a while now, but I was taken with the blend of dramatic and documentary elements because this felt more tactile in how you present the past – if there’s pictures, they’re on a wall of a house, and you’re taking people back to the places they once were. What was it like to make this feel as if it lived in the present?

At its core, this is a ghost story about a dead man and the men and women who experienced and were involved in this incredibly traumatic event and how they carried that trauma to this day. So for the most part, to tackle past tense stories, you have to be able to animate them viscerally and emotionally to make them feel immersive, and it was trying to blend the rigor of documentaries and journalistic reporting with a big sweeping cinematic experience that puts you on the border, in the gunfights, in the room where the torture and murder takes place. And documentaries need stars every bit as much as films need stars, so it’s a lot about winning the confidence and trust of [the subjects] to put them in a safe environment where they can crack into the deepest recesses of their souls and know that it will be lovingly attended to. I don’t want to sound grandiose about it, but it’s a powerful thing to be entrusted with somebody’s story and their deepest secrets and fears and traumas and hopes and dreams, and it’s a sacred undertaking, getting them to the place where they can be themselves, so it’s about directing a performance.

After “The Seven Five” and “Operation Odessa,” it was interesting to have some women in the mix here with Hector’s mom, who doesn’t seem like an obvious subject, and Kiki Camarena’s widow Geneva. How did they come to be involved?

It was really important to me to have those voices in the sense that somebody famously asked Scorsese, “You make these movies about gangsters and criminals – how do you humanize them? How do you make the audience give a damn?” And the answer was you give them a mother. So it occurred to me that when I met Hector, let’s explore his relationship with his mother because you get this tough guy, macho gunslinger out in the streets, but who’s this guy? Everybody lives in their childhood, and when I met her, she was this fantastic, almost mystical character, [where I thought] that’s our way into understanding and exploring him emotionally. And then in regards to Kiki’s widow, she’s been through among the worst traumas that anybody could ever deal with, and I wanted to approach giving Kiki a voice in a sensitive and loving way, so her window into him and her window into herself were critical to conjuring that side of it.

Was there anything that changed your ideas of what this could be?

This one was so full of astonishing surprises at every turn, sitting down with each of those subjects in isolation and hearing them reveal the details, thinking like, “Wow, this is the guy that kidnapped Kiki Camarena and laid hands on him, put him in the car and drove him to the house.” That was a powerful one, and conjuring that gun fight with Hector in Limoncito, the longest gun battle in DEA history. Then frankly, the most astonishing and harrowing one of all is the one at the end of the series with the unnamed informant comes forward and detonates the information that this [breach that led to Camarena’s kidnapping] wasn’t an accident, there was collusion by a member of his own team and a betrayal at the center of it. That left me pretty speechless.

This story is so big and rich and complicated and when you step into a conspiracy — not a conspiracy theory, but a genuine conspiracy — it’s a dark hole with no bottom and you have to keep going and going and going. And at the very last moment where something or someone comes forward with a piece of information [that becomes] like the secret heartbeat of the whole thing, that was very much the case with that final informant, where you have this first person, firsthand source saying, “This is what I saw, this is what happened.” You have to stop everything and pay attention to it because that’s the storytelling doing what it wants.

You see all these people unburdening themselves of something they’ve carried with them for so long. What’s it like to show it to them?

It’s absolutely terrifying every time I do it. I was afraid I was going to get shot in the cinema of “The Seven Five” when that first premiered or Tarzan was going to hunt me down for “Odessa” or Hector, who is not someone you would want chasing you, was going to be chasing me for the rest of my life. I always just hope and pray I’m doing everything I can to honor the deepest parts of these people and what they’ve shared, so whenever they’re gratified to see it, I’m relieved because it takes a lot to make these things.

“The Last Narc” is now streaming on Amazon Prime.