HSBC has found itself mired in international scandal after a massive leak by a former employee revealed how the London-based bank’s private Swiss subsidiary took deposits between 2005 and 2007 from warlords, arms traffickers, drug dealers, dictators and a host of politicians past and present. The exposé, published by French newspaper Le Monde and the International Consortium of Investigative Journalists (ICIJ), documents around 30,000 accounts with a collective worth of nearly $120 billion.

Highlighted in the disclosures are “the bank’s dealings with clients engaged in a spectrum of illegal behavior, especially in hiding hundreds of millions of dollars from tax authorities,” as ICIJ reported on Sunday.

There’s a prominent Russian aspect to the story as one of the named depositors is billionaire oligarch (and personal friend of Vladimir Putin) Gennady Timchenko, who was sanctioned by the United States in March 2014 for his role in providing “material or other support to” Russian government officials. (There’s a rumor that sometime in the 1990s, Putin and Timchenko, who holds Finnish citizenship, were arrested in Helsinki for drunk and disorderly conduct; a rap sheet is said to exist with the two men’s mug shots.)

Timchenko’s designation carried the blockbuster revelation that Gunvor, the Swiss commodities trader he co-founded, was itself a vehicle for Putin’s personal self-enrichment: “Putin has investments in Gunvor,” the U.S. Treasury notice stated, “and may have access to Gunvor funds.” Not long before the sanctions were announced, Timchenko, who is worth an estimated $14.1 billion, was said to have divested his stake in Gunvor. Then, in November 2014, it was announced that the U.S. Attorney’s Office for the Eastern District of New York, helped by the Justice Department, was investigating Timchenko for money laundering. In 2013, Reuters disclosed that Timchenko had hired lobby firm Patton Boggs to persuade the U.S. Export-Import Bank, the export credit agency of the U.S. government, to finance his purchase of up to 11 Gulfstream luxury jets—a deal that was eyebrow-raising at the time and is now rendered illegal by sanctions.

Timchenko wasn’t the only Russian keeping accounts with HSBC, however. As reported by the newspaper Vedomosti, Yury Kosarev, the former chairman of the Fund for Social Insurance and the deputy head of the Federal Health Care Agency, kept $2.5 million in the Swiss bank between 2006 and 2007. Pyotr Nizdelsky, Russia’s former deputy energy minister, placed deposits in the bank in 2004, the same year he quit government service. Along with his wife Lidiya Nidzelskaya, he held $11 million between 2006 and 2007, the leaked documents reveal.

The most intriguing Russian angle to the HSBC embarrassment involves Hermitage Capital, once the wealthiest investment fund in Russia and today known more for its crusading founder, Bill Browder, who has just released his memoir, Red Notice. The book details his years-long struggle with the Russian government, starting with his expulsion from the country in 2005, to the defrauding of Russian taxpayers of $230 million using stolen Hermitage companies, to the wrongful arrest and jailhouse murder of his tax attorney Sergei Magnitsky, who uncovered the theft and then fell victim to its perpetrators.

The interior and tax ministries, the Federal Security Service (FSB)—the successor to the KGB—and the Russian judiciary all joined in a conspiracy with a transnational organized crime syndicate to pull off this heist and murderous cover-up, which culminated with the posthumous “trial” of Magnitsky in 2013. (Browder was also tried in absentia and sentenced to nine years.) In 2012, Congress passed the Sergei Magnitsky Rule of Law Accountability Act, which aims to ban and freezes any stateside assets of Russian officials credibly accused of gross human-rights violations.

The Magnitsky affair is a 21st-century Kirov assassination or Reichstag fire in that it not only raised the curtain on Putin’s thermidor but seems to serve as a reference point to every major scandal or controversy involving state officials, including the sacking of former Russian defense minister Anatoly Serdyukov.

Before becoming persona non grata in Russia, as well as the target of its numerous attempts extradition attempts, Browder made a name for himself in Moscow by investigating corruption in major Russian companies—the biggest being Gazprom, the state-owned gas giant, which had sold off valuable gas fields between 1996 and 1999 for pittances. In one astonishing example, 53 percent of Sibneftegaz, a Gazprom subsidiary, was sold to a group of buyers—including the brother and nephew of Gazprom’s then-CEO Rem Vyakhirev—for 0.3 percent of its estimated cost. Browder’s discoveries not only caused a whirlwind in the financial press and markets, they also—initially—impressed Putin, who fired Vyakhirev in 2001 and replaced him with Alexei Miller, who runs Gazprom to this day.

As recounted in Red Notice, Hermitage Capital began as a partnership between Browder and Edmond Safra, the billionaire investor, in 1996. However, Safra, via his Republic National Bank, sold his stake in the fund in 1999—to HSBC, making the now embattled bank Browder’s new institutional partner as well as the administrator of Hermitage. Browder, a British citizen, leaned on Clive Bannister, the CEO of HSBC’s private bank, to help resolve his visa difficulties with Moscow. HSBC, Browder wrote, was “an enormous bureaucratic bank…wholly uninspiring when it came to moneymaking, but…world class when it came to dealing with the British establishment.” Nothing came of that effort, but it was the least the bank could do given that it would go on to recoup over $200 million from Browder’s fund in the subsequent two-year period: According to its own financial statements, HSBC made $117 million in 2006 and $108 million in 2007, all from the partial sale of Hermitage investments.

Nonetheless, during that same period, HSBC’s Swiss bank was only too happy to take deposits from Gazprom officials or their offspring. Farit Gazizullin, a company board member since 1998, was one. The former head of the Russian Ministry of State Property, he and his wife, according to Vedomosti, held $3.6 million in an HSBC account between 2006 and 2007. Vadim Sheremet, the son of Vyacheslav Sheremet, former deputy director of the management of Gazprom, “opened an account in the Swiss bank in July 2006, and from 2006-2007 maintained $10.4 million there. During the time when Gazprom was led by Rem Vyakhirev, Vadim Sheremet owned shares in several delivery and contract companies of Gazprom along with Vyakhirev’s children and then-prime minister Viktor Chernomyrdin,” the newspaper also noted.

This wasn’t illegal, it was just scummy.

“This is rather typical behavior of big banks,” said Tom Mayne, a campaigner with the London-based transparency watchdog Global Witness. “They don’t care about the source of their money, even though in HSBC’s case, they knew quite well from Hermitage what Gazprom was up to—ceding business to these mysterious intermediary companies without any reason to do so. For HSBC to then disregard that information and turn around and accept the money from the very people Hermitage was exposing seems very dubious. It’s like an arms dealer selling arms to both sides.”

Mark Galeotti, a specialist on Russia’s security services and the Russian mafia, agrees. “What this really demonstrates is that the parallel challenge to global organized crime is global organized malfeasance. There are so many activities which we would frankly think of as immoral but nonetheless a combination of laws not having caught up yet and financial institutions gleefully taking advantage of that opportunity. In the case of Russia, it’s a particular problem because what it means is for years we have complained about the opacity and corruption of the Russian system while making money off it and also facilitating it.”