In 1964, Irwin Lipkin became one of the first employees at a small New York trading firm called Bernard L. Madoff Investment Securities.
Five decades later, Lipkin, 77, is set to be sentenced on Wednesday in Manhattan federal court for falsifying records, marking the end of the criminal case stemming from the collapse of Madoff's multibillion-dollar Ponzi scheme more than six years ago.
Lipkin is the last of 15 people who either pleaded guilty or were convicted at trial in connection with the fraud, which cost investors approximately $17 billion in principal.
Madoff, 77, who is serving a 150-year sentence after pleading guilty in 2009 to masterminding the fraud, has always insisted he acted alone.
Prosecutors have conceded that Madoff alone knew the full extent of his deception. Even his deputy, Frank DiPascali, who was intimately involved in the fraud, testified he believed Madoff had hidden assets to cover customers' liabilities almost until the end.
See photos of Madoff's victims and more from the trial:
Bernie Madoff trial
With final defendant, Madoff criminal case comes to an end
Victims of Bernie Madoff's massive Ponzi scheme, Morton Chalek, 91, standing, a WWII vet, and his friend Fran Reiss, 79, a retired educator, pose in the apartment they share, on Thursday, Dec. 5, 2013 in New York. With the fifth anniversary of Madoff's fraud approaching, Chalek and Reiss are among a legion of former investors still struggling to move on after seeing their life savings go up in flames. (AP Photo/Bebeto Matthews)
Jack and Melba Cutter are shown in their home in a subdivision outside the north-central Colorado city of Longmont on Saturday, June 27, 2009. Jack Cutter, who is 80 years old, has returned to work as a clerk at a meat counter in a supermarket after he and his wife invested their savings with a small firm last year that sent the money into feeder funds created by Bernie Madoff. (AP Photo/David Zalubowski)
David Friehling, the former accountant for con artist Bernard 'Bernie' Madoff, center, exits federal court following a sentencing hearing in New York, U.S., on Thursday, May 28, 2015. Friehling, who signed off on phony audits of Madoffs firm for decades, became the fourth person tied to the $17.5 billion fraud to avoid prison after aiding prosecutors. Photographer: Sam Hodgson/Bloomberg via Getty Images
NEW YORK, NY - OCTOBER 08: Daniel Bonventre (L), former director of operations for investments, working under Bernie Madoff, arrives at Federal Court, to begin a trial being brought against him by the federal government on October 8, 2013 in New York City. Federal prosecutors allege that Bonventre worked for Madoff and knowingly supported the largest Ponzi in history, which Madoff led. Prior to the collapse of the scheme, Madoff reported that his accounts held approximately $68 billion, when they in fact only held a few hundred million dollars. Madoff was found guilty and is serving a 150-year sentence in North Carolina. (Photo by Andrew Burton/Getty Images)
NEW YORK, NY - DECEMBER 20: Brother of convicted Ponzi king Bernard Madoff ,67-year-old Peter Madoff, arrives at U.S. District Court in Manhattan on December 20, 2012 in New York City. A plea agreement makes a 10-year prison term all but certain for Madoff who was convicted after he pleaded guilty to conspiracy and falsifying books and records of an investment adviser. (Photo by Spencer Platt/Getty Images)
Daily News back page February 16. 2011, Headline: The Knew Nothing - Fred Wilon and Mets partner Saul Katz didn't know about Bernie Madoff's multi-billion dollar sam, says the man who ran it all. Madoff comes to Mets owners defense. Lupica: with nothing to gain why would Bernie lie now? (Photo By: NY Daily News via Getty Images)
Annette Bongiorno, a former secretary at Bernard L. Madoff Investment Securities LLC, exits federal court in New York, U.S., on Friday, Jan. 14, 2011. Bongiorno, 62, is among five people facing charges of helping Bernie Madoff defraud investors of billions of dollars in a Ponzi scheme. Photographer: Michael Nagle/Bloomberg via Getty Images
Daniel Bonventre, former director of operations for Bernard L. Madoff Investment Securities LLC, exits federal court in New York, U.S., on Friday, Jan. 14, 2011. Bonventre, 63, is among five people facing charges of helping Bernie Madoff defraud investors of billions of dollars in a Ponzi scheme. Photographer: Michael Nagle/Bloomberg via Getty Images
UNITED STATES - JUNE 29: Ira Sorkin, Bernie Madoff's lead attorney, arrives at manhattan federal court in New York, U.S., on Monday, June 29, 2009. (Photo by Jin Lee/Bloomberg via Getty Images)
UNITED STATES - MARCH 14: Daily News front page March 14, 2009, Headline: WHAT BERNIE MADE OFF WITH, Reviled Madoffs own more than 826M in planes, homes & assets, Bernie Madoff,Bernard Madoff. Rihanna's back in town, Rihanna (Photo by NY Daily News Archive via Getty Images)
NEW YORK - MARCH 12: Investors DeWitt Baker (R) and Judith Welling, who had invested with financier Bernard Madoff, are interviewed outside a Manhattan Federal courthouse after Madoff was sent by a judge to jail to await sentencing on March 12, 2009 in New York City. Madoff was ordered to jail after pleading guilty to a multibillion-dollar financial fraud scheme and could end up with a sentence of 150 years in prison. (Photo by Rick Gershon/Getty Images)
NEW YORK - MARCH 10: Accused $50 billion Ponzi scheme swindler Bernard Madoff exits federal court March 10, 2009 in New York City. Madoff was attending a hearing on his legal representation and is due back in court Thursday. (Photo by Mario Tama/Getty Images)
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Madoff tearfully confessed to him that he didn't "have any more goddamn money" in the firm's final days, DiPascali said in 2013 while testifying against five former colleagues.
But prosecutors have used millions of documents and the cooperation of key co-conspirators to prove that while Madoff was the architect, he had plenty of help.
The task was complicated by the sheer scope of the fraud and involved poring through countless paper records, since the scheme began before computers were widespread.
"It was a fraud that lasted for 40-something years; it involved thousands upon thousands of customers," said former prosecutor Matthew Schwartz, now a partner at Boies Schiller & Flexner, who helped lead the Madoff investigation. "It was very difficult to know where to start."
Lipkin, who pleaded guilty to falsifying records as the firm's controller, has asked for probation, citing his declining health, while prosecutors have requested prison time.
Five employees took their chances with a jury: back-office director Daniel Bonventre, portfolio managers Annette Bongiorno and JoAnn Crupi and computer programmers George Perez and Jerome O'Hara.
They were convicted on securities fraud and other counts in March 2014, following a six-month trial that was one of the longest ever white-collar criminal trials in New York.
Lawyers for the five, who are appealing, say they were duped by one of history's greatest con men, just as investors, auditors and regulators were.
"Nobody knew what he was doing," Andrew Frisch, Bonventre's lawyer, told Reuters. "These are uneducated, or thinly educated, functionaries who basically see him as a god."
Those assertions may have helped persuade U.S. District Judge Laura Taylor Swain not to impose lengthy prison terms, instead sentencing them to between 2-1/2 and 10 years.
Prosecutors criticized those sentences as too light and have taken the unusual step of appealing.
Besides DiPascali, six defendants cooperated with prosecutors and were rewarded with non-prison sentences. DiPascali died in May before his sentencing.
As part of the criminal investigation, the Justice Department has also recovered $4 billion for victims, including $1.7 billion from Madoff's longtime bank, JPMorgan Chase & Co (JPM.N), as part of a deferred prosecution agreement.
Over the years, there was speculation as to whether the government would expand its criminal case to others, including major Madoff clients and other firm employees.
Last year, Reuters reported that prosecutors were still considering a case against Madoff's son, Andrew. He died of cancer a few months later.
Madoff's other son, Mark, committed suicide on the second anniversary of his father's arrest.
No Madoff customer was ever criminally charged. In 2010, Irving Picard, the trustee seeking to recover victims' funds, and prosecutors reached a $7 billion civil settlement with the estate of Madoff client Jeffry Picower, who died in 2009.
Picard has recouped more than $10 billion and is still pressing civil claims against members of the Madoff family and other parties.
For a list of the defendants and their sentences in the Madoff case, click here
(Reporting by Joseph Ax; Editing by Noeleen Walder and Meredith Mazzilli)