In early December 2014, just as he was allegedly embarking on a scam to bilk his friends and family out of at least $95 million, Andrew Caspersen, then 37, participated in a "networking" event at the Princeton Club, on West 43rd Street in Manhattan. Given by and for alumni of the exclusive Groton School, northwest of Boston, the event, titled, without irony, "From Schoolroom to Boardroom," was a typical gathering for the East Coast elite to slap backs, mate connections, and further already prosperous careers—skills that Andrew had honed to a fault over the years.

That evening Andrew radiated prosperity and achievement. A managing principal at the Park Hill Group, in New York, he was dressed in a dark pin-striped suit, starched white shirt, and yellow rep tie. As some in the audience recalled, he was quiet, a bit arrogant, but approachable and happy to talk about his own success. "He was prototypical of what you, by your senior year, would want to become," says one Groton graduate who was there that night. "He just kind of had everything."

Andrew's job at Park Hill—then a division of the Blackstone Group, the global financial behemoth—was to advise investors and private-equity firms on the arcane art of buying and selling limited-partnership interests in other private-equity firms. His was a specialized skill, which he had learned as a corporate lawyer on Wall Street and then as a partner for eight years in the New York office of Coller Capital, a London-based asset-management firm that specializes in buying such limited-partnership interests. At Park Hill, Andrew was being paid handsomely for this work: $3.68 million in 2015 and $4.5 million in 2014, according to federal prosecutors. "He was that symbol of the guy who worked at a law firm and then figured it out and translated that into a private-equity firm and then became a partner at another firm," says Stephanie Borynack Clark, Groton class of 1992 and the proprietor of the Wally Findlay Galleries, in New York.

Fifteen months later the purported charade was over. On Saturday, March 26, at 5:30 P.M., at New York's La Guardia Airport, federal agents arrested Andrew in front of his wife and two young children. He was charged with one count of criminal securities fraud and one count of criminal wire fraud. The family was returning from a vacation in the wealthy enclave of Jupiter Island, Florida, where Andrew's 71-year-old mother now lives full-time and is a doyenne of the social scene. According to The Wall Street Journal, upon his arrest Andrew said little and surrendered quickly. His wife, Christina Frank Caspersen, the director of global investor relations at Anheuser-Busch InBev, "appeared to be in a state of shock as her husband was escorted away," the paper reported.

She was not the only one. As news of Andrew's arrest spread throughout the financial world, there was utter disbelief. On Jupiter Island, it went down hard. His mother is a "beloved figure" there, according to Nathaniel Reed, whose family developed this spit of land in southeastern Florida, now home to the likes of Tiger Woods and Dick Fuld, the disgraced former Lehman Brothers C.E.O. "Old Wall Street in shorts" is how Fred Whittemore, a former longtime partner at Morgan Stanley and a business partner of Andrew's late father, Finn Caspersen, once described the island. "[It's] tragic for her and the rest of her family," Reed says. "Her grandchildren have all been here for spring vacation, and they are the most delightful people.... So you can imagine this has had a colossal impact on her. But she's showing her usual bravery."

People who know Andrew were desperately trying to understand what could have possessed someone who seemingly had it all to allegedly cross so many boundaries into immoral and criminal behavior: after all, not only is he charged with stealing millions of dollars but he supposedly took it from his close friends and family—including his mother—by constructing an elaborate scheme using the tradecraft he had learned on Wall Street. It depended on a desperate confidence game, in which he supposedly exploited his victims' refusal to believe that someone of his pedigree and education, someone who was part of the Club, would betray them.

The question remains: Why would he do it?

Some who know him believe he had become unhinged by two great tragedies: the death of his fiancée in the 9/11 attacks on the World Trade Center and the grisly suicide of his father, in 2009. "This poor kid, he can't be a bad guy," says someone who knew the Caspersens professionally. "He didn't go to Groton and Princeton and Harvard Law by being either a dope or a bad guy. But your dad kills himself in desperation and your fiancée dies in 9/11, there's some demons there. It's kind of like a Shakespearean thing."

The American Dream

On paper, anyway, no one had a more charmed life than Andrew Warden Westby Caspersen. His father, Finn Michael Westby Caspersen, was chairman and C.E.O. of Beneficial Corporation, a large consumer finance company. In 1998 he sold the company to Household International for $8.6 billion worth of stock, which made him wealthy by any measure.

Finn was a bit of a dandy, prone to formalwear and top hats. The New York Times once described him as "Gatsbyesque." Among his favorite pastimes were four-in-hand horse-drawn-carriage driving and Olympic-level horse jumping. During his 20-year reign as the driving force behind the U.S. Equestrian Team, to which he donated some $1.3 million, American riders and drivers earned 71 medals, including 25 gold, in the Olympics, World Championships, and Pan American Games.

"This poor kid, he can't be a bad guy," says someone who knew the Caspersens. "There's some demons there. It's like a Shakespearean thing."

Finn wanted people to think he was even more immensely wealthy than he was. "He needed to be the richest guy in the room," says a person who knew him well. He had beautiful homes in Andover and Bernardsville, New Jersey—the really nice parts of the state—in Westerly, Rhode Island, and on Jupiter Island. He also had a penchant for getting things named after himself and his family, There is the Caspersen Student Center at Harvard Law School, plus a Caspersen Room on the fourth floor of the school's library, and the Caspersen Rowing Center, in Princeton, New Jersey, where the nation's elite rowers train for the Olympics. At the Peddie prep school, in Hightstown, New Jersey, where Finn went to high school and later served on the board, there is the Freda Caspersen dormitory, named after Finn's immigrant Jewish mother; the Caspersen Campus Center; and the Caspersen History House. There is the Caspersen School of Graduate Studies, at Drew University, in Madison, New Jersey, and even the Caspersen Beach, in Venice, Florida, which was once part of the family's real-estate holdings on the Gulf Coast. Charles Poliak, a friend of Andrew's who trained at the Caspersen Rowing Center, recalls of it, "For me, that was like, 'Oh, that's so cool. That must be Andrew's family.'And I didn't even realize that his family was so successful until I saw that."

Such naming rights don't come cheap. Between January 1998 and December 2008, Finn gave away a little more than $14 million in more than 1,500 separate gifts. Multiple published reports say he pledged $30 million to Harvard Law School and was the biggest donor in its history, but foundation records show that, in the 10 years prior to his death, he gave 92 separate gifts to the law school, ranging in size from $66 to $529,031.25, which totaled only about $1.5 million. (Finn had a habit of making many small gifts a day in odd amounts. For instance, on August 6, 2008, he gave Peddie $21.86.)

Andrew was the youngest of Finn's four sons (the others are Finn M. W. Caspersen Jr., 46, a senior executive at the Peapack-Gladstone Bank, in New Jersey; Erik M. W. Caspersen, 45, a partner at 9W Capital Management, in New York; and Samuel M. W. Caspersen, 43, a managing director at Brock Capital Group, an investment-banking boutique, in New York). At Groton, Andrew rowed crew and was a co-captain of one of the most storied football teams in the school's history. Four years later the football coach, John Lyons, was still talking about him as "the best player he'd ever coached," remembers one Groton graduate. "He was a big guy on campus, really. Honestly, he had everything going for him," says Poliak. "Maybe like the all-American guy."

After Groton, Andrew went to Princeton, where he met Catherine "Cat" MacRae, whose family had founded the Wall Street law firm LeBoeuf, Lamb, Greene & MacRae. They fell in love and were going to be married. "He fell for Cat's interesting combination of being attractive, very nice, and funny—very funny," her mother, Ann, explained to Dennis Smith, the author of an oral history about families who lost loved ones in the 9/11 terrorist attacks. Andrew recalled how Cat would "light up" the dinner table at Princeton's Ivy eating club with "her charm and self-deprecating wit."

In April 1998, while Andrew was still at Princeton, his father announced the sale of Beneficial Corporation to Household Financial Inc. The 1997 Beneficial proxy statement, the last before the merger was announced, shows that Finn controlled 5.8 million shares of Beneficial stock. Since Household was paying around $145 in stock per share, many people assumed that the sale of Beneficial made Finn worth some $840 million—an estimate being widely reported to this day. But his actual stake was closer to one million shares— not six million—giving him a windfall of only around $150 million. (The balance of the shares, worth nearly $700 million, was owned by trusts that Finn controlled or of which he was a trustee.) Even if he was nowhere near being a billionaire, Finn still wanted people to believe he was one. "That's the image he wanted to project," the person who knew him well says. "Actually, the family fortune was less than $100 million."

After graduating from Princeton, in 1999, Andrew went off to Harvard Law School, as had his three brothers. A year later, in 2000, Cat MacRae went to Goldman Sachs as a young analyst. Soon thereafter, she accepted a job working for Fred Alger Management. "She was happy there," her father said. "Unfortunately David [Alger] selected the ninety-third floor of the WTC as their office site." Like all her colleagues who were working on that floor on September 11, 2001, Cat died in the terrorist attacks.

A memorial service was held for Cat at St. Andrew's Dune Church, in Southampton. "Just before the service began, the rain subsided and the 40-mile-an-hour gusts settled into a gentle breeze," Andrew wrote in the Princeton alumni magazine. "And during the service, as the speakers recalled Cat's boundless love and generosity, sunlight flooded the church in a way church parishioners had never witnessed."

After graduating from law school, like his father before him, Andrew joined the white-shoe firm Dewey Ballantine as an associate. In 2003, after a year or so, he left the firm, along with his mentor, Frank Morgan, to work for Coller Capital in its New York office. (Morgan declined to be interviewed about Andrew.)

Around this time Andrew's father, a former tax lawyer, stalled dodging his taxes on both his ordinary income and his capital gains, according to the person who knew him well. The New York Times reported that he "might have owed as much as $100 million in back taxes and fines or, possibly, even have faced prison." Says the person who knew him well, "He had tax problems due to foreign accounts.... He feared criminal prosecution."

On the afternoon of Labor Day 2009, Finn shot himself in the head with a Smith & Wesson .38-caliber revolver. Police found his body at 3:01 P.M., next to a large green generator by a reservoir near Rhode Island's Shelter Harbor Golf Club, which he had founded with other partners even though he had no interest in golf.

"On his person," according to the police report, the local police found his Black Berry, his driver's license, and $360 in cash. There was a handwritten note in the pocket of his dress shirt. According to the police, the note said that he "was tired, diminished and in constant pain, and that he did not want to be a burden to his loving family."

Charity Begins at Home

Figuring (correctly) that Andrew's 2016 arrest would once again dredge up questions about why his father had killed himself, the family sent around to some media outlets—but not to me, despite repeated requests—a two-page letter, written in 2015, from a Chicago attorney hired by the family. (In 2010 I wrote about the death of Finn Caspersen for Vanity Fair.) It purports to show that the I.R.S. reviewed Finn's tax returns for the four years between 2005 and 2008 and found that he owed unpaid taxes in 2008 of only around $75,000, including a $12,000 penalty. But the person close to Finn notes that the I.R.S. review does not include 2009, the year of Finn's death, and that the I.R.S. did not ask for more probably because it had concluded he had no money to pay the taxes. "It only makes sense that he was insolvent," this person says, a view that is consistent with what Andrew's attorney told the federal court during Andrew's March 28 appearance about Finn's destitute financial condition at the time of his death.

Another rumor that persists to this day is that Finn had kidney cancer and was tired of suffering from it. "He didn't have cancer," the person who knew him well says. "Caspersen wasn't healthy. He could barely walk. He ate too much, drank too much. I don't think he smoked. But he did not have cancer_He was in trouble and there was one way out." (Andrew's brother Sam Caspersen did not respond to a request for an interview; nor did a longtime Caspersen-family attorney on tax and estate matters.)

One example of the confusion surrounding Finn's fortune or lack thereof can be found in the financial documents related to the O. W. Caspersen Foundation for Aid to Health & Education, which Finn ran from 2001 until his death. In an accounting of its finances for the year 2007, the foundation listed assets of $17.4 million. A year later, after Finn's death, the trustees of the foundation—Finn's widow plus his three sons aside from Andrew—said its assets had decreased to $3.2 million. The following year the foundation listed 32 pages of grants, totaling $14 million, made by Finn. "The foundation failed to report these contributions on previous [financial-disclosure forms] and is doing so now," according to a note in the filing.

Alan Cantor, a consultant to nonprofits, studied the 2009 Caspersen tiling at V.F. s request and was shocked by it. "It is the damnedest thing I've ever seen," he says. "Private foundations have considerable leeway in how they run their operations, but in exchange the federal government demands near-total transparency. Every transaction has to be reported annually—each investment, any honorarium for board members, the top salaries, of course every grant. It's unheard of for a foundation to report a decade worth of grants after the fact. Finn Caspersen must have treated the foundation as his personal charitable checkbook, and it's astonishing that none of this activity was reported until after his death."

After leaving Coller Capital, in December 2011—and a year-long stint working for one of the family investment firms—Andrew joined Park Hill, in January 2013, as a managing director. According to a statement filed with the S.E.C. by PJT Partners—the investment-banking boutique that was later merged with Blackstone's investment-banking business, including Park Hill, in September 2015—Andrew started to misbehave around the time of the Groton alumni event, in December 2014. From then until his arrest, the firm wrote, "Caspersen conducted a number of unauthorized and unlawful transactions outside the scope of his employment with Park Hill. They consisted of schemes Caspersen presented to his family and personal network to make investments in entities formed by him with names resembling parties in legitimate Park Hill transactions."

According to criminal and civil legal things by both the United States Justice Department and the Securities and Exchange Commission, along with various published reports, Caspersen's "schemes" were essentially to offer investors something that was obviously too good to be true: a 15 percent return on an investment in an $80 million secured-credit facility that paid quarterly interest and could be redeemed at any time with 90 days' notice. Not even the King of the Ponzi Scheme, Bernie Madoff, had made such a bold promise, preferring to offer his investors around a 10 percent annualized return.

According to prosecutors, to make the completely fictitious investment opportunity seem genuine, Andrew dressed it up in the minutiae that he had learned over the years that are typical of Wall Street deals. He served up pages upon pages of mundane and boring legal documents that were just close enough to actual deals Park Hill was working on that anyone not doing his or her due diligence might be seduced. And with Dewey Ballantine, Coller Capital, and Park Hill on his resume—to say nothing of Groton, Princeton, and Harvard Law—who would ever doubt the legitimacy of what he was offering?

Allegedly, his first victims—when Park Hill was still part of Blackstone—were members of his own family, including two of his three brothers and his mother, and also several close friends, who, according to the PJT Partners statement, invested "approximately $14 million in Andrew's schemes."

"Imagine if your brother or your best friend approached asking for a relatively small investment into something he did every day," one of Andrew's acquaintances told The Wall Street Journal. "This is a guy who had established himself as a respected and sophisticated investor for more than ten years at some of the most respected firms. Why wouldn't you put your money in?"

But that was just a prelude for a bigger alleged fraud. Soon, Andrew went back to the well. According to Kurt Hafer, a criminal investigator in the Southern District of New York, on October 24, 2015, Andrew contacted one of his Princeton classmates, James McIntyre, by then a managing director at Moore Capital, a hedge fund run by billionaire Louis Bacon. Andrew offered McIntyre—who was investing on his own and on behalf of the $195 million Moore Charitable Foundation—a piece of the too-good-to-be-true $80 million loan from Park Hill to Coller Capital, with the 15 percent return. He claimed he had already secured commitments of $30 million from "his family office," as well as from "two others." His story sounded just real enough to be plausible. But then Andrew took an additional step toward implausibility by telling McIntyre, a four-year lacrosse player at Princeton, that Coller didn't need the loan after all, but since it had already committed to the borrowing, Coller would still take his money and make the 15 percent interest payments.

Why McIntyre fell for this scenario is not clear, especially when a bunch of others by this point—including other Groton and Princeton alumni—had passed. (McIntyre declined to comment.) On November 2, Andrew sent McIntyre an e-mail with wire-transfer instructions for the investment. The next day, he sent him a bunch of bogus legal documents—using the name "Irving Place III SPV"—that had a whiff of authenticity about them. A fictitious "John Nelson" signed the documents.

On November 5, McIntyre wired $25 million to an account controlled by Andrew at Bank of America: $24.6 million came from the foundation and $400,000 was McIntyre's own money. Hafer has noted that, instead of the $30 million that Andrew told McIntyre he had already received toward the $80 million loan, his Bank of America account had only $2.51 million in it. "Caspersen then simply took control of the funds for his personal use," the S.E.C. claimed.

This personal use involved covering up another scam. According to PJT Partners' statement, Andrew had billed a Park Hill client for $8.9 million worth of actual work done but had the unsuspecting client send the fee "to an account controlled by him using an elaborate structure of entities, domain names and bank accounts that he created." When PJT Partners' billing staff wondered what had happened to the fee, Andrew wired them the $8.9 million from his new stash at Bank of America, according to Hafer. Also on November 6, Andrew transferred $17.61 million from the Bank of America account to his personal brokerage account at JPMorgan Chase. For the next month or so, Andrew allegedly gambled with the money on options based upon an S&P 500 exchange-traded fund. These were bad bets, and Andrew quickly lost $14.5 million when the market moved against him.

To keep all his balls in the ah Andrew kept moving money around among various brokerage accounts. "He used over a dozen bank accounts in the names of these shell companies," the government asserted at his bail hearing. Whatever he was doing, it wasn't working. By the end of 2015, his brokerage account at JPMorgan Chase had a "net loss of approximately $25 million," says Hafer.

But Andrew was not yet deterred. On January 4, 2016, he wired the Moore foundation $587,225 from his Bank of America account—something like the quarterly interest on its $25 million investment. But that interest payment, Hafer wrote, came from the relatively little money Andrew still had left in his Bank of America account, which by March 18 had less than $40,000 in it.

Fool Me Once

On March 1, 2016, Andrew supposedly tried to pull McIntyre in a second time. He wrote his classmate that another large investor, "a family office founded with oil/gas money," wanted its $25 million investment in the Irving Place S.PV. back. He claimed that his family would make a $5 million investment this time around toward replacing that $25 million. He was hoping McIntyre and the Moore foundation were good for the remaining $20 million.

Andrew concocted a new round of fake legal documents and sent them to McIntyre, according to the complaint. This time, though, McIntyre said he wanted to speak with the John Nelson, at Coller Capital, who had signed the documents and was vouching for the security that backed the loan. Scrambling, Andrew sent an e-mail to McIntyre and to John Nelson at a fake e-mail address similar to Coller Capital's, and then set up a conference call for March 7. But that plan backfired when someone at Moore Capital told McIntyre that the John Nelson e-mail domain had been set up 20 minutes after McIntyre had asked for the conference call, and that it wasn't the same as Coller Capital's actual domain name. McIntyre was also informed that no one by the name of John Nelson worked at Coller Capital.

Around two P.M. that day, McIntyre joined the conference call as scheduled. He spoke with someone purporting to be John Nelson, who claimed to be a Coller Capital vice president. McIntyre asked for his phone number, but the person refused to divulge it. After the call, McIntyre got an e-mail from "John Nelson" with a telephone number said to be Nelson's.

McIntyre then called Andrew and explained to him what had just transpired. "Strange," Andrew responded, offering to get to the bottom of it, according to the criminal complaint. Soon Andrew called McIntyre back to tell him that he was right about the domain name and that "John Nelson" was formerly an "outside administrator" for Coller in Guernsey, a notorious tax haven. Andrew claimed things "don't look very good" for the analyst who had come up with the John Nelson e-mail address, adding, later that day, that upon the advice of counsel he couldn't say much more about this shady John Nelson. But he apparently assured McIntyre that the foundation's $25 million investment was safe.

At this point McIntyre said he wanted his money back. After a few more conversations, Andrew, on March 11, sent an e-mail to McIntyre affirming that the foundation's money would be returned by the end of March, "if not sooner." Needless to say, it never was.

Andrew made one final attempt to raise cash on March 7, just as McIntyre says he was figuring out that he had been conned. Back in October, Andrew had written to someone he knew at Kohlberg Kravis Roberts (K.K.R.), the big buyout firm, asking if it wanted in on the investment. But K.K.R. was asking a lot of questions that Andrew couldn't easily answer, so it passed. On March 7, Andrew contacted K.K.R. again, offering the firm a $50 million investment in the $80 million loan. Again K.K.R. didn't take the bait. (K.K.R. declined to comment.)

The jig was up when Moore Capital informed Park Hill and PJT Partners about Andrew's "investment scheme." At his bail hearing on March 28, Andrew was released from federal custody after posting a $5 million bond, secured by the $ 1.1 million equity in his home in Bronxville, New York; his coop on East 62nd Street, in Manhattan, worth between $1.5 million and $2.3 million; and $50,000 in cash. It turned out that since his Manhattan apartment was a co-op it couldn't be pledged as security. So the amended security for the bond was his home in Bronxville, $1 million in cash, plus the signatures of "three financially responsible persons," who presumably would be on the hook for the money if Andrew jumped bail: his wife; his brother Finn; and another Princeton friend, Blackford "Beau" Brauer, and his wife, Suzy.

The two counts against Andrew carry maximum sentences of 20 years in prison each, and the fine could be as much as twice what was lost, or around $50 million. He is said to be working with the government on settling the charges against him. "The game is up," says the person close to the family. "He's got no way out, as far as I can see."

Andrew's former attorney, Daniel Levy, told the court on March 29 that Andrew recently had "thoughts" about suicide, without elaborating. One can only hope that he doesn't make the same desperate choice his father did.