Updated from 10:54 a.m. EDT

There's no doubt about it: Federal authorities are seeking to make an example of Frank Quattrone, the former

Credit Suisse First Boston

investment banker who is charged with trying to impede a grand jury investigation of his former firm.

Prosecutors were pretty adamant in making that point at a press conference Wednesday afternoon, when they announced the filing of three obstruction-of-justice charges against Quattrone, who had helped turn CSFB into a powerhouse investment bank in the technology sector during the latter half of the 1990s.

The prosecutors said it didn't matter that the grand jury investigation into some of CSFB's investment banking practices ended in November 2001 without any criminal charges being filed. Prosecutors also have no plans to reopen that investigation, even though they contend that some documents were destroyed because of the alleged obstruction of justice.

What matters, federal authorities said, is that Quattrone allegedly tried to subvert the justice system by directing his underlings to destroy firm documents. And that, prosecutors say, is something that can't go unpunished, because grand jury investigations of corporate wrongdoing often rely on a degree of honesty by the people being investigated.

"It's critically important that people follow the rules," said James Comey, U.S. attorney for the Southern District of New York. "If you or your company get a subpoena ... don't even think of playing games."

Comey said law enforcement doesn't have the resources to send out a team of investigators, armed with search warrants, every time it requests documents from a company. So it's critical for prosecutors to come down hard on corporate defendants that don't abide by the "honor system" on which the grand jury process must rely.

"The federal grand jury process is something of a voluntary system," said Comey. "It is an honor system that will be guarded with an iron fist of enforcement."

Ira Sorkin, a New York criminal defense attorney, likened the government's decision to file charges against Quattrone to the obstruction-of-justice case that prosecutors brought against Arthur Andersen in the Enron investigation. "Obstruction is very serious and the courts view it as a very serious matter," he said.

Not surprisingly, Quattrone and his lawyers see the obstruction charges as something completely different -- an attempt by law enforcement to make a crime where one was never committed.

"Frank Quattrone is innocent," said John Keker, the banker's lawyer, in a prepared statement. "Only prosecutors who see the world through dirty windows would take a one-sentence email supporting company policy and try to turn it into a federal criminal case." Keker said his client, arraigned Wednesday and released on his own recognizance, intends to prove his innocence at trial.

The case against Quattrone stems from a brief email he sent to his associates in December 2000. On the surface, the email seems innocuous because it merely reminds people of CSFB's document retention policy and urges them to destroy any unnecessary documents so they can't provide ammunition to any plaintiffs' lawyers that might sue the firm over some of its initial public offerings.

But it's the timing of that email that bothers prosecutors: The email was sent as a federal probe into CSFB's investment banking practices was heating up -- a probe that prosecutors allege Quattrone knew about. In fact, they allege that a day before the email was sent, CSFB's then general counsel told Quattrone about the grand jury investigation and said that federal authorities would be serving subpoenas seeking documents.

Again, that criminal investigation into CSFB's policies for allocating shares in hot IPOs to institutional customers ended without any charges being filed. But CSFB, a division of

Credit Suisse Group

(CSR)

, did pay a $100 million fine in January 2002 to resolve a related civil investigation brought by securities regulators.

And since that date things have only gotten worse for the 47-year-old California resident.

Early last month, when the potentially incriminating emails were discovered, Quattrone resigned under pressure from CSFB. In March, the NASD charged the former technology investment banker with violating securities rules by doling out shares in hot IPOs to corporate executives in a bid to win investment banking business for CSFB. The NASD, formerly known as the National Association of Securities Dealers, had been investigating allegations of "spinning" against Quattrone for months.

Regulators also charged Quattrone with overseeing a system at CSFB that put pressure on research analysts to tout stocks of companies that did banking business with CSFB.

It's quite a tumble for a man who at one time was one of the most respected investment bankers in Silicon Valley.