(CNN)When interrogating an informant about a major drug cartel, freshly baked cookies aren’t exactly on the list of requirements.

But they don’t hurt, either — and not for the reason you might think.
Former Assistant US District Attorney Bonnie Klapper became infamous for having homemade confections on hand as she investigated Colombia’s Norte Valle cartel in the late 1990s and 2000s. Yet it wasn’t a deliberate ploy to lure answers as much as it was a way to show some humanity.
Back then, Klapper and her partners in the multi-agency El Dorado Task Force were working tirelessly to connect the dots between a New York money laundering operation and the Norte Valle cartel. At the time, the notoriously violent cartel was thought to be responsible for an estimated 60% of the cocaine coming into the US. As a mother of two young sons, one of whom was born with special needs, Klapper found herself baking to shake off the stress.

      On the surface, it was a regular store — but that was a front

    “I’d wake up in the morning, there’d be cookies and I’d bring them in, and I fed the agents,” she said. “If I brought them into an interview, what was I going to do? Not feed the defendant?”
    After all, people are people, whether they’re caught up in a drug operation or not.
    “The best prosecutors put themselves in the shoes of the defendant. They’re human beings, just treat them with the same respect with which you would want to be treated,” Klapper said from her home on a warm September afternoon. “Everything you do in life, it has to be fair. It has to be kind. There has to be a recognition of why people end up where they end up. As a prosecutor, unless you take the time to learn why, you’re not doing your job. It’s as simple as that.”
    The same can’t be said for the takedown of the Norte Valle cartel. It took more than a decade of dogged and sometimes defiant persistence as Klapper and her colleagues chipped away at layers upon layers of narco bosses. There were death threats from a drug kingpin, and skeptical superiors who questioned shutting it down.
    But it wasn’t in their nature, Klapper said, to just let the job go unfinished. She was going to follow the money until she could take the cartel down from the very top — and she did.

    The road to El Dorado

    Raised on the south shore of Long Island in New York, Klapper had always been the kid who wanted justice and wasn’t afraid to demand it. If she got in trouble at school for fighting, it was because she’d punched the class bully to protect another kid.
    Yet at first, it looked like her life’s path could be in the arts, or maybe journalism. What was always clear was that whatever her future held, it would be found 3,000 miles away from home.
    “I was happy to leave New York as soon as I could,” she said. “Berkeley, California was the antithesis of everything I was brought up with.”
    Her father encouraged her to secure her future with a trade, and she settled on law. When she graduated from the University of California, Berkeley Law School in 1982, the public defender’s office was her first stop — except they weren’t hiring. Before long, she found herself drawn to the other side of the courtroom aisle.
    “I saw the prosecutors at the US Attorney’s office in LA, where I was clerking for a judge, and I saw that they really did — at least at that time — look to be fair,” Klapper said. “And that’s a principle that’s guided me my whole life. Sometimes it’s gotten me in trouble with bosses, who wanted me to seek unreasonably high sentences, or unreasonably aggressive convictions. But if it wasn’t right, I just wasn’t going to do it.”
    With some perseverance and some luck, Klapper joined the US Attorney’s Office in California’s Central District. Soon enough, she was recruited to join its money laundering unit.
    The money cases were harder, but she discovered that’s also why she liked them.
    “How hard is it to do a street-level drug case?” Klapper says today. “The money cases, you really had to think, ‘Why is it being done this way? How can I show the source of funds?’ It’s far more sophisticated, and I just took up a passion for it.”
    Money laundering is essentially finding a way to make the funds you’ve earned through illicit means appear to have been earned lawfully — to make the “dirty” money “clean.” The cases could become complex, but Klapper had uncovered her specialty, and her fascination with money laundering was right on time. By the late 1980s, she found herself moving back East with a husband and a growing family, and the Eastern District of New York was looking for someone with her exact expertise.

    North of the Valley

    As Klapper began work as an assistant US district attorney in New York, seismic shifts were happening much farther south.

      DEA agent: To catch a cartel boss, follow the money

    Colombia had witnessed the bloody rise and fall of the Medellin cartel, which had been run with terrifying force by Pablo Escobar. There was also the Cali cartel, which became even more powerful after Escobar’s death in 1993.
    Yet what some may not realize is that a third Colombian cartel emerged in the 1990s to take the crown as the kings of cocaine. When the Cali organization fell apart in 1995, the Norte Valle cartel stepped in.
    As a DEA supervisory special agent puts it in the CNN Original Series “Declassified,” the Norte Valle was “just as mean and nasty and formidable as Escobar.”
    When a war broke out between the Medellin and Cali cartels in the ’80s, the Cali organization put together a group of assassins to take out their rivals.
    “You know who those individuals were?” the DEA agent continued. “The future members of the Norte Valle cartel.”
    But around 1997, when Klapper first heard about suspiciously large sums of money being sent from a money remittance company in New York to Colombia, the name Norte Valle didn’t immediately come up.
    The case was sniffed out by members of the El Dorado task force, which included the New York City Police Department, state troopers, the IRS and the US Customs Service. The task force’s job was to investigate financial crimes and money laundering, and they’d been tipped off that something strange was happening at a Tele-Austin outpost in Queens.
    The task force began surveillance, and they quickly realized that the money transfer business — which, like a Western Union or a MoneyGram, offers an easy way to send money overseas — was somehow sending tens of millions of dollars in a year to Colombia without the customer base to show for it.
    “We knew it was drug money because of the volume,” Klapper said. “We saw that all the money was going to (the Colombian cities) Armenia, Pereira and Cartago. So, in various legal documents we filed, we called it the Armenia-Pereira-Cartago cartel, because we didn’t know what it was! But then, when the earliest witnesses started to flip, they said, ‘Well, that’s the Norte Valle.’ Which had really not been on anyone’s radar.”
    But what the Norte Valle may have lacked in press, they made up for in severity.
    “Nothing touched Pablo (Escobar’s) level of violence because he targeted civilians,” Klapper said. “But in terms of retribution and violence, the Norte Valle was unparalleled.”

      How a money laundering investigation led to a violent cartel

    There were clear risks to pursuing a cartel made up of hit men and assassins, but Klapper kept her head down and focused on the work, juggling parenting with uncovering the paper trail.
    “My older son was born with psycho-neurological disorders,” Klapper said. “He’s been variously diagnosed since he was two-and-a-half with early onset bipolar disorder, attention deficit disorder (and) intermittent rage disorder. And my husband frequently traveled for work, so it was me.”
    Klapper is quick to note that, unlike many, she and her husband were able to afford help. And as she dug deeper into the money laundering and drug trafficking investigation, the family also leaned on the support of the task force and Klapper’s partner, Romedio Viola — her work husband, as she jokingly calls him.
    “I can’t tell you how many times I’d get the call from school: ‘You need to come take (your son) home, he’s having a bad day,'” Klapper recalled. “Romedio and I would get in his car, drive to the school, bring him back home, put him in the front of the TV with his snack, and work. I couldn’t have done it without people who were understanding of the situation.”
    Yet not everyone was. There was the boss who told her that a woman with a child like hers shouldn’t have this kind of job, and another who told her that the Norte Valle case was a waste of time.
    In response, “I just kept doing my job,” Klapper said. “My partner and I, we would say, we were like sharks. We keep moving around, and ultimately we’ll bump into something good.”

    Who’s afraid of a cartel boss?

    Like pieces on a chess board, Klapper and her team strategically went after each member of the cartel. They didn’t want to just shut down the money remittance stores; they wanted to dismantle the entire organization. The plan was to build cases against the leadership, extradite them to the US and have them stand trial for money laundering and drug trafficking.
    By the late 2000s they’d apprehended two of the top bosses of the Norte Valle cartel — and one who remained, a man who went by the name “Patemuro,” was out for blood.
    “A prosecutor called me and said, ‘Bonnie, I think you and Romedio need to get down here to interview this witness. He’s in Miami and he’s saying some very frightening things,'” Klapper said. “We went down to interview him, and he told us that he’d been in the cell block in Colombia with Patemuro, and he was talking about how he was going to kill us, asking anybody if they knew the best way to hire an assassin to get to an American prosecutor.”
    It took months, Klapper said, to get protection. But when US Marshals showed up as her security detail, they were with her around the clock. (No cookies, but the marshals did get fresh-baked muffins every morning.)
    While Klapper’s life had been threatened before, this time was different: She’d investigated this death threat herself, and she knew it was real. And yet, through the handful of months she was under the watchful eye of her security team, she says still didn’t feel any fear.
    “It’s like a piece of my brain is missing that doesn’t know you’re supposed to be scared of those things,” Klapper joked. “I tried to laugh; I thought it was funny. I think I only was scared at the time that the judge pronounced the sentence: Patemuro got 40 years, and that’s when it hit me what we had been dealing with. I remember crying for two minutes, and then saying, ‘OK! Let’s move on to the next one now.'”

    The ’empress of money laundering’

    Over the years-long investigation, Klapper and her team prosecuted dozens of people in connection to the Norte Valle case, starting from that suspicious money remittance storefront all the way up to the chiefs of the drug cartel.
    “We’re talking upwards of 50 people, and we only have two fugitives who weren’t caught,” Klapper said, the pride evident in her voice.
    Her persistence in following the flow of money became so legendary, her coworkers gave her a royal new nickname.
    “The team of agents that I was working with, one of them said, ‘You’re the queen of money laundering,'” Klapper said, chuckling. “And someone else said, ‘No she’s not the queen, she’s the empress.'”
      While she laughs at their sense of humor, she also doesn’t shy away from the title. According to Klapper, who’s since retired as a federal prosecutor and now works in private practice, there were very few agents during that era who tackled cases in the way she and the task force did.
      “The whole case was made on paper and witnesses,” Klapper said. “We had financial records. We had lots of money seizures. But we never had any drugs. We took down an entire cartel and never seized one kilo.”

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