Responding to Comey’s statements that “no reasonable prosecutor” would pursue a case against presidential candidate Clinton, Quattrone retorted on Twitter, “Says the man who once indicted me over a 23-word email that encouraged my team to save subpoenaed documents.”

Quattrone, who these days is riding high in Silicon Valley and on Wall Street after brokering a string of recent M&A deals including the pending $26.2 billion sale of LinkedIn (LNKD) to Microsoft (MSFT) and HomeAway’s acquisition by Expedia (EXPE), was referring to an email he sent more than 15 years ago, in December 2000. The banker is happy to joke about the indictment episode now because it’s a joke at Comey’s expense: The charges against Quattrone, which Comey brought when he was still the U.S. Attorney in Manhattan, were eventually dropped in 2006 after the banker won an appeal overturning his conviction for obstruction of justice.

Today Quattrone is executive chairman of Qatalyst, the boutique investment bank he founded in 2008 and of which he served as CEO until relinquishing that role in January. Qatalyst has recently risen up the ranks of the Wall Street M&A league tables, advising on six deals worth more than $31.6 billion in the first half of this year—more than double the value of the deals it worked on in the same period last year, according to Mergermarket. That makes Qatalyst the No. 15 dealmaker in the U.S. in Mergermarket’s rankings so far this year, edging out storied tech investment banks like Allen & Company. Indeed, LinkedIn would be the third company Qatalyst has advised in a sale to Microsoft this year alone. Qatalyst is also reportedly advising ride-hailing app Lyft, though it’s unclear whether the Uber competitor is exploring a sale or another type of deal. Legendary venture capitalist Marc Andreessen once endorsed Quattrone on Twitter, tweeting that he and Qatalyst’s current CEO George Boutros “are astonishingly good at their jobs.”

But Quattrone wouldn’t have made it this far had the U.S. government successfully prosecuted him for his own email brouhaha—a scandal that a decade ago threatened to ban him from Wall Street.

Like with Clinton, emails were at the heart of Quattrone’s case, though in a different way. It was 2000, in the months after the dot-com bust, and regulators were investigating the forces that contributed to the tech bubble, including the bankers behind some of the most hyped initial public offerings of the boom. At the time, Quattrone led the technology group at the U.S. investment banking arm of Credit Suisse (CS), which was “one of the world’s leading underwriters” of tech IPOs, as described by Comey in legal documents at the time.

The government suspected that Credit Suisse was basically extorting clients, and artificially pumping up the shares of tech companies, by demanding “exorbitant” commissions to get special access to IPO shares. (Neither Quattrone nor Credit Suisse were ever found guilty of that allegation.) As investigators subpoenaed a slew of documents relating to the deals, Quattrone maintains that he encouraged his team to follow standard document protocol. But Comey zeroed in on a certain email which he used as the basis to charge Quattrone with obstruction of justice.

That email, which was actually 22 words according to case documents, followed another banker’s email to the technology group reminding them of the firm’s document retention policy and urging them to “catch up on file cleaning” before going away for the holidays. Quattrone seconded the message, writing, “Having been a key witness in a securities litigation case in south texas (miniscribe) i strongly advise you to follow these procedures.” The original email also noted that file cleaning would have to be suspended in the event of a lawsuit, “since it constitutes the destruction of evidence.” But the preface of the memo indicated that the group was somewhat concerned that a lawsuit might actually be coming: “With the recent tumble in stock prices, and many deals now trading below issue price,” the original email began, the bankers were expecting lawyers to mount “an all out assault on broken tech IPOs.”

Says the man who once indicted me over a 23-word email that encouraged my team to save subpoenaed documents https://t.co/GYRzWDOhk0

— Frank Quattrone (@FrankQuattrone) July 5, 2016

A spokesperson for Quattrone tells Fortune, “Mr. Quattrone’s email endorsed an existing document policy that called for subpoenaed documents to be saved. It’s a matter of public record that before sending it, [Credit Suisse] lawyers never informed him that the subpoenas they had received called for his team’s documents, and never warned him that those documents needed to be preserved.”

Comey tried to read between the lines, alleging that Quattrone willfully destroyed evidence, but ultimately he could not make the charges stick. (The other Quattrone email mentioned in the court documents is even shorter, and chides the sender of the original email for writing in a preliminary draft of the memo, “Today, it’s administrative housekeeping. In January, it could be improper destruction of evidence.” Quattrone rejected that part of the draft, responding with eight words: “You shouldn’t make jokes like that on email!”)

Quattrone’s rebuke of Comey’s lack of action against Clinton drew cheers in conservative circles, who would rather have seen the government go after the Democratic presidential candidate. As for whether Quattrone himself actually opposes Clinton, or simply harbors a grudge against Comey, the answer may be a bit of both. The banker and his firm declined to comment further or answer questions about his politics, though a spokesperson tells Fortune that “Mr. Quattrone’s tweet reflected his personal views and not those of Qatalyst.”

In March, Quattrone described himself on Twitter as “a life long Republican,” though he expressed disappointment in his own party. (Quattrone, born to an Italian immigrant family, proudly publicizes that heritage. Immigration has been a divisive topic among conservatives this election cycle.) So far, he has made only minor contributions to 2016 political campaigns—to candidates on both sides of the aisle—though he has not written checks to either Donald Trump or Clinton. He donated $2,700 to New Jersey Governor Chris Christie’s presidential campaign, and another $2,700 to the congressional campaign of Jimmy Panetta, a California Democrat, according to campaign finance records. In the last presidential election in 2012, he donated $25,000 to Republican hopeful Mitt Romney and $35,800 to Barack Obama.

@SpeakerRyan As a life long Republican it's sad to see the Party earn a well deserved Darwin Award for causing its own death like this

— Frank Quattrone (@FrankQuattrone) March 16, 2016

When Quattrone transitioned from CEO to the executive chairman role at Qatalyst earlier this year, he was celebrating a record 2015 for the bank, and said, “I remain firmly committed to Qatalyst’s long-term success, and look forward to continuing to drive our strategy and advise clients on their most important strategic priorities. Besides the LinkedIn and HomeAway deals, in the last year he has personally advised Jasper on its $1.4 billion acquisition by Cisco (CSCO), Informatica on its $5.3 billion buyout deal by a Canadian pension fund and others, and other deals.

Editor’s note: This article has been updated to clarify the government’s allegations against Quattrone and add a comment from his spokesperson.