The city of San José, Costa Rica, is a sprawling gray mess that doubles as the sex-tourism capital of Latin America. Thanks to legalized prostitution, parts of downtown look like Disneyland for horny, middle-aged Australians. The urban center is a mix of shopping malls, semi-rises, and fast-food outlets that separate streets of grinding poverty from pockets of conspicuous wealth.

The Costa Rica Fortress John and Ann Bender's haunting Costa Rica fortress. See Photos →

Ann Bender to Be Tried Again Costa Rica's justice system has overturned Ann Bender's acquittal. Update →

Rich expats gravitate to a suburban area called Escazú, because that’s where the embassies are and because misery loves company. It was there, in a high-security apartment complex for short-term diplomats, that I first met Ann Bender, Central America’s most captivating accused murderess.

By this point—October 12, 2012—nearly three years had passed since the strange and bloody death of Ann’s husband, John Felix Bender. John, 44 when he died, was known on Wall Street as the troubled genius who’d quit the billionaire track without explanation in 2000 and retreated to a fortified compound in the Costa Rican jungle. His end came just after midnight on January 8, 2010, in the top-floor bedroom of a circular mansion that looked like something Colonel Kurtz would have imagined in his dreams. John was naked in the bed he shared with Ann, who was then 39. The cause of death was a single pistol shot to the back of the head.

The only witness to the shooting was Ann, who’d spent a dozen years as the yin to John’s yang. Together they’d built the tropical Xanadu that surrounded the mansion: a 5,000-acre wildlife preserve built on and around the highest mountain in the most forbidding rainforest in Costa Rica. They nursed each other through a shared battle with manic depression, and together, thanks to a dicey blend of extreme isolation, mental health challenges, and conflicts with enemies real and imagined, the Benders had apparently gone mad.

On the night in question, Ann was found stroking her dead husband’s hand while saying, “I tried to stop it, but I couldn’t.” She claimed John finally made good on his long history of suicidal behavior. But investigators came to doubt her—partly because of forensic evidence that didn’t appear to match Ann’s story. The day I met her, she was awaiting trial on a murder charge that could put her away for 25 years.

At Ann's insistence I was driven to our designated meeting place by her security chief and all-around fixer, Jose Pizarro, whose quiet warmth and casual style—close-cropped hair, mustache, polo shirt—did nothing to diminish his standing as a man to be obeyed. Having previously served as chief of Costa Rica’s civilian security force, Pizarro, 45, couldn’t drive ten feet without a cop shouting, “Generale!” or “Don Pizarro!”

I complimented the tattoo on his arm. A cobra. “Sí,” he said. “I did it myself.”

Pizarro’s English was rudimentary, but his message was clear.

“This case is—how you say?—bullshit. Bullshit from motherfuckers, sí?”

Inside the building, Pizarro escorted me up to a two-bedroom unit. “Ann feels safe here,” he said. “And she don’t feel safe anywhere in Costa Rica.”

Several questions sprang to mind. First: Costa Rica? Weren’t we in the peaceable kingdom of eco-lodges, zip-line tours, and romantic episodes of The Bachelor? No juntas, death squads, or drug cartels. No standing army. Nothing but democracy, beaches, and coffee, right?

Second: Was I heading to meet a human train wreck? Ann, during our brief e-mail correspondence—which had been initiated by her brother, who’d contacted me at the suggestion of a reporter I knew in Detroit—told me she was suffering from various physical ailments, among them Lyme disease and a potentially lethal blood clot situated just above her heart. Her afflictions and legal problems had caused her to be, by her own admission, a model of instability. There had been hospitalizations, talk of suicide, and anxious late-night e-mails hinting at dangers and conspiracies.

And then she walked in.

“First question,” she said. “Can I hug you?”

Her life was no longer her own. The Costa Rica criminal court had seized her passport and ordered her to show her face on a weekly basis. The trustee cited John’s death as grounds to seize her purse strings.

She was a tiny thing—five-three, 105 pounds, but in a sleek, elegant way. Black halter, black skirt, black suede boots; piercing brown eyes and unlined caramel skin; hair pulled back in a shiny ponytail. She displayed only one marker of ill health: an adhesive bandage, located just above her right clavicle, discreetly concealing a catheter that dripped small doses of morphine into her veins, to keep her pain and moods in check. “I’m not stoned,” she said. “Trust me.”

Despite her moods, which could be epic, Ann typically evinced a kind of cockeyed pluck, a hummingbird baseline that stood in contrast to mania. Sometimes she seemed almost too sane for her own good, displaying pointillist recall of details perhaps best forgotten. Blood splatters and bank balances, pillow talk and court testimony: she held it all at her fingertips, literally.

“Make way for the bag lady,” she said.

Ann was pushing a shopping cart stuffed with legal case files, transcripts, and research materials. “When I say ‘I know,’ I will be careful,” she said. “If it’s conjecture, I will say so. Otherwise, operate under the presumption that I have proof.”

Ann’s stockpile pertained to a trifecta of separate but related legal proceedings. Along with the murder rap, she was a suspected jewel smuggler. Police, while investigating John’s death, had found millions of dollars of “undocumented” gems inside the Bender mansion. Meantime, Ann was playing offense against a Costa Rican legal trustee she blamed for swindling her and John’s fortune and sandbagging her to the point of indebted servitude.

The net effect: her life was no longer her own. The Costa Rica criminal court had seized her passport and ordered her to show her face on a weekly basis. The trustee cited John’s death as grounds to seize her purse strings. Now Ann lived on a bare-bones allowance covering little beyond monthly expenses, part of her medical care, and rent on this apartment.

For more than two years, Ann said, she tried to keep her story out of the news, lest she come off as the Ugly Americana in a country she still loved. “But enough,” she said. “I didn’t kill my husband, and I don’t deserve this. That’s why I made the very careful decision to tell you everything. I’m angry. And when I’m angry, I do a lot better than when I’m sad. Sad means passive. And that’s exactly how the powers that be want me.”

She launched into a complicated explication of a financial matter. Then, just as swiftly, she pumped the brakes.

“Too fast?” she asked

A little.

“Where should I start?”

The beginning.

She nodded and smiled. “John,” she said.

John Bender was brilliance descended from brilliance—the oldest of two sons born to Paul and Margie Bender. Paul, a noted legal scholar, held prominent posts in the Clinton administration’s Justice Department and at two major law schools, Penn and Arizona State. Both parents say John’s intelligence was evident very early.

“When I would take the kids grocery shopping, he’d be figuring out price per ounce,” Margie says. “When he was in kindergarten, he’d say, ‘Mom, you could get a better price if you bought a pound.’ ”

“His use of words was precocious,” Paul says. “He didn’t speak early. Then he started speaking in complete sentences. He never did anything until he was absolutely sure he could do it perfectly. He taught himself to read but didn’t display the ability until kindergarten. He said if he’d done so earlier, he feared I would stop reading to him.”

John won math competitions but lost his temper, typically with teachers or students who failed to question everything. The world’s youngest individualist could play well with others, as long as they played his game; failing that he’d bolt, melt down, or both. He was a gifted percussionist who refused to audition and an A student who rejected Harvard because he hated the interview. “People were not John’s favorite thing,” Margie says. When he was in his early teens, John asked, “Mommy, is it alright if I don’t have a birthday party?”

As a teenager, John spent his free time hanging around Penn’s physics department, later enrolling as a student there. He was on track to a physics career until the summer of 1987, which he spent working at the Lawrence Livermore National Laboratory, a government-sponsored facility in Northern California that works with high-tech weapons. This was during the Reagan-era arms buildup; John concluded that most of his job opportunities in physics would involve “helping out with new ways to kill people.”

His future was decided the day he visited a friend at the Philadelphia Stock Exchange, where he discovered options trading—a numbers game he could win or lose based solely on his talents. Almost immediately, he began buying options with his own money. He did well enough that friends staked him with funds to make a go of it.

John was Ann’s ideal specimen. He had massive shoulders and thighs the size of armadillos; his face, with its strong cheekbones and wide-set features, projected a quiet intensity that could play as aloofness or arrogance.

John, then 22, was built like a football player—six-foot-three, 250 pounds—and on the floor, with its shouters and showmen, fellow traders didn’t know what to make of the shy young behemoth wearing medical scrubs instead of pants. “It was the same pair for a while,” says Bernie Hirsh, one of John’s former floormates. Another ex-trader, Jonathan Kaplan, pegged John as a wallflower with dark shadings. “I definitely recall the social anxiety,” Kaplan says. “He mostly was quiet, listening.”

They both thought he was brilliant, and in time John came clean about the scrubs. “I wore them so everybody would think I was an idiot,” he told Hirsh. “I wanted guys to trade with me.”

At the heart of John’s success was his embrace of game theory, a data-driven mode of strategic decision making based on the anticipated actions of others. Ever the contrarian, he found anomalies in the probability theories most traders viewed as gospel. He used his predictive advantage to successfully bet against the conventional wisdom.

From 1992 to 1996, John’s returns were through the roof. So it was only a matter of time before his hedge fund, Amber Arbitrage, attracted some big whales, among them the famed mogul George Soros. By the time John turned 32, in 1996, he was on pace to become a billionaire by age 40.

They met in March 1998, at a place called Golden Mountain Farm. The 100-acre spread was located in the lush countryside west of Charlottesville, Virginia. John had purchased the lot two years earlier, telling friends he needed to live “somewhere green.”

Ann, then 28, was a new and exotic addition to rural Virginia. Her looks and style seemed more in keeping with her birthplace, Rio de Janeiro, where she was the second of two children born to Kenneth Patton III, an executive at Chase Manhattan who worked in Rio, and his wife, Gigi. “I wouldn’t say I had a platinum spoon or a gold spoon in my mouth,” Ann says. “Silver-plated, perhaps.”

Her youth was marked by private schools, parties, and white-sand beaches. Then, in classic expat-brat fashion, Ann moved from Rio to Lisbon to London to New York. She earned a degree from Ithaca College, did a stint working at a fine-arts college in Baltimore, and experienced a kind of epiphany. “My mood swings and bipolarity had started ruling my existence,” she says. “By the time I was 22, I’d been pretty much always up and down, up and down. I don’t think my move to Virginia was an incorrect one, but it was definitely something I did in a manic moment.”

Ann arrived in Virginia scared, isolated, and frail. She made friends—including one who invited Ann over to meet her live-in ex-boyfriend, John Bender.

John was Ann’s ideal specimen. He had massive shoulders and thighs the size of armadillos; his face, with its strong cheekbones and wide-set features, projected a quiet intensity that could play as aloofness or arrogance. Or both. Ann had always been “drawn to strong men, physically and mentally,” says her mother.

“I like to feel safe,” Ann says.

John, when he first met Ann, noticed her trembling hands right away. “Can I get you some water?” he asked.

“Oh, I’m just on an enormous dose of lithium,” she said, in her unfiltered way. “I’m severely bipolar. So if I act strange, that’s why.”

John, equally unfiltered, volunteered that manic depression had colored his life, too, though to somewhat different effect. His depressions could be every bit as apocalyptic as Ann’s. But where Ann never enjoyed the sparkly side of the condition, John’s mania often fueled long periods of inspiration and productivity. He also suffered from obsessive-compulsive disorder, so it was no wonder he happily put in 20-hour workdays.

Virtually overnight, the preserve turned into a summer camp for monkeys, sloths, and parrots; every morning, in the foggy darkness before dawn, the Benders woke to the impatient squawks and stares of macaws dangling upside down from the ledge of their roof.

Ann and John, during that first day, found too many commonalities between them to count. They shared family histories best described as “complicated.” Mood disorders had brought havoc to both the Pattons and the Benders. Ann’s parental conflicts were mostly related to that; John’s were mostly tied to his father, who sometimes questioned John’s impulsive choices.

Still, both sets of parents had warmly encouraged their children’s passions for things like far-flung travel and wildlife. John, as a child, had always preferred the company of nonhumans. As an adult, he kept dozens of stray cats on his farm. When people asked why, he’d reply, “Because they don’t talk.”

John, who was treated for a mild aneurysm in 2000, told Ann that once he racked up enough money, he would get out of trading, sinking much of his fortune into a bigger, better version of the green idyll he enjoyed in Virginia. He told Ann he’d been scouting potential locations in Costa Rica and Brazil.

“I’ve already been to Brazil,” she pointed out.

The town of La Florida de Barú looms 2,200 feet above the Pacific, on the southwestern edge of Costa Rica—arguably the country’s most undeveloped region. Prior to 1998, many of the 100 or so people who lived there lacked electricity; most residents lived in weather-beaten farmhouses or tiny cabinas accessible only by narrow dirt roads that turned to slop during the rainy season.

To live there was to submit to the primacy of the rainforest: an area so vast (hundreds of square miles), so wild (deadly pit vipers, warring monkey tribes), and so damned out there that it remained impervious to the gringo land grabbers buying up the northern parts of the country. Nobody bought into this corner of Costa Rica. Not even Costa Ricans.

Then, in 1998, along came these two rich yanquis who dropped $10 million for 5,000 acres in the middle of the highland jungle. The land was composed of separate farms that produced a meager coffee crop and a few grazing areas for cattle. The main issue was accessibility, or lack thereof, thanks to the combination of rugged mountains and a massive escarpment that cut the place off from the world.

“Perfect,” John said. “This is home.”

Construction took four years, with an army of 500-odd workers completing a vast compound that included four separate houses, a moat, and a helipad. The Benders gave it a name that they mistakenly thought was a species of local plant: Boracayan.

Admittedly, plopping a giant house into the rainforest doesn’t sound like environmentalism, but the Benders mitigated that by making the structure eco-friendly, reforesting to undo the soil damage from coffee farming, and operating the place, first and foremost, as a refuge—the region’s only large-scale private haven for endangered, abandoned, or injured animals.

Teams of armed rangers were hired to chase off poachers, who previously had used the land as a hunting ground for birds and animals whose meat fetched top dollar at local markets. Ann hired six full-time caretakers and brought in vets when needed. Virtually overnight, the preserve turned into a summer camp for monkeys, sloths, and parrots; every morning, in the foggy darkness before dawn, the Benders woke to the impatient squawks and stares of macaws dangling upside down from the ledge of their roof.

But the sight of sights was the main house, which sat atop the area’s highest mountain, at roughly 2,500 feet. The interior structure took up 8,000 square feet. The total living area—the porches, sculpture garden, waterfall, reflecting pool stocked with tilapia, and more—approached 120,000 square feet.

Refuge employees hadn’t seen him in weeks, except for one or two long-distance glimpses of “Don John” carrying Ann from room to room. “Gently,” one of the guards recalls. “Like carrying a sick child.”

The house benefited from Ann’s light decorating touch and John’s design master-stroke: no external walls. The only thing standing between the Benders and the elements was a series of roll-up storm doors. Whenever they were inside—cooking, taking a bath—they were outside. And whatever was outside came in, unabated: birds and lizards and insects, wind and fog. To lie in bed was to sleep in the clouds.

The master bedroom took up the entire top floor. Below, on the third floor, was an office space furnished with a large desk, a few chairs, and a computer. Despite John’s “retirement,” he was constitutionally unable to quit the game altogether. A satellite dish linked him to the outside world.

But every evening, just before sunset, John and Ann had a thing. They’d go to the second floor, which housed a chef’s kitchen and a large dining area. They’d migrate out to a balcony that faced west. From there they could sometimes see all the way to Panama (on the left) and Nicaragua (to the right). And on the best nights, as they peered out over the Pacific, they would see an endless blue sea dotted by whales.

It was ideal. Then it all started going to hell.

The troubles began in late April 2001, on a sleepy country road just outside La Florida. John and Ann were in their Ford F-350, on their way to buy seeds, when a car boxed them in. “John Bender!” the driver shouted. “You’re coming with us!”

Two men aimed guns at John’s head, ordered him out of the truck, and started forcing him toward their vehicle. During the confusion, the gunmen fired two warning shots, and one of the rounds sprayed up dirt near John’s legs. Ann screamed. Suddenly, the assailants identified themselves as plainclothes police and arrested John. Hours later, in the local police station, a man John had never met handed him a summons and said, “John Bender, you’ve been served.”

The summons was related to an ugly legal battle John was engaged in at the time. It involved a New York financial manager named Joel Silverman, who had invested seed money in Amber Arbitrage in the mid-nineties. In 2001, Silverman alleged that John had verbally promised him a 25 percent cut of the company’s value, which by then ran in excess of $500 million.

Silverman tried to paint John as a tax mercenary who used foreign tax shelters to hide his money from both Silverman and the U.S. government—an assertion that wasn’t entirely inaccurate. John hated the IRS so much that he renounced his U.S. citizenship when he and Ann moved to Costa Rica. He claimed that Silverman was behind the abduction, stating in a deposition that he had suffered “at the hands of Silverman’s agents.”

Meanwhile, the Benders became unpopular among the Costa Rican locals. Some were hunters tired of getting chased by men with guns; others were just pissed that they hadn’t been hired to work at Boracayan.

A security expert was blunt, telling the Benders: “My advice to you is to get the hell out of here.” After spending three months in Canada, the couple returned and hired security guards with paramilitary training.

Still, Ann couldn’t quite shake her fear and agitation. This triggered a cycle of manic depression, a physical breakdown, and an emergency hysterectomy a few months after the incident with the gunmen.

A second crisis materialized one night in 2002, when guards exchanged gunshots with an armed intruder who was seen heading toward the house. After the intruder fled into the night, Ann spiraled downward. And when she crashed, John did, too. “He was very upset about Ann,” says Brad Glassman, a Washing-ton, D.C., attorney who handled some of John’s legal business. “And when things weren’t working for John, he could go off the deep end. He got very manic, very out there.”

Paranoia took hold. When John wasn’t searching for cures to what ailed Ann, he was fortifying the home and buying weapons. At one point, they again fled the country, this time to New Zealand for three and a half months. Again they were advised to cut their losses and move somewhere else. But no. “We chose Costa Rica,” Ann says. “We were in love.”

Their commitment was rewarded in 2003, when they sponsored and hosted a research team made up of botanists from the U.S., Costa Rica, and Germany. In one week, the team discovered three new species of orchid on the preserve. One belonged to a particular genus (Gongora) known to be uniquely difficult to classify or understand. The team named this species Gongora boracayanensis.

By 2008, John and Ann’s legal battles had been settled, and they had invested the bulk of their liquid assets—roughly $90 million—in a Costa Rica–based trust that promised several benefits. For starters, Costa Rica now rivaled the Caymans as a shelter for foreign wealth. More important, the trust insulated the Benders from future claims against their personal assets, including Boracayan. Legally, they were now mere servants of the trust, which would be administered by a local attorney John had come to respect. The trustee’s name was Juan de Dios Alvarez.

By the time John died, his closest neighbor was Paul Meyer, an American expat who owns a small tree farm in La Florida. Some nights, while driving through the area, Meyer would catch a good view of Boracayan. Mostly it was dark, he said, but the top floor of the main house—the master bedroom—would be glowing “like a clerestory window.”

The glow came from one of Ann’s design touches. She craved bright, colorful lights—the Benders collected Tiffany lamps—a desire that was especially strong during her dark periods, which were increasing in frequency and duration. John would do anything to improve her mood, which explained why, by 2010, the number of Tiffany lamps in their bedroom had reached 550.

Ann’s health had taken a sharp turn for the worse. Now, on top of the Lyme disease and bipolar disorder, she was having trouble walking. John sent her to various specialists in San José, but nothing helped.

John started breaking down, too. Such was the extremity of his devotion to Ann, to fixing her, that he saw his failure as a failure of character. “He was always fanatical about trying to help Ann,” says Pete Delisi, a stockbroker who was one of the few people John kept in touch with. “The abduction, her illness—he felt like he’d failed her.”

That month, when Ann was off seeing a doctor, John sent her an e-mail in which he despaired about everything, from small health maladies to his larger mental condition:

I’m losing my fucking mind right now. First sick again and now this shit. Today is a total fucking nightmare and tomorrow will get worse. Just when I was feeling I could finally learn to be happy, now I get this and I want to be dead. I feel so fucking horrible. I want to kill everyone and then me.… I deserve to die.

Ann describes that period this way: “Every day, during the last six weeks, we would sit down and he would take all the medications we had and put them into piles and say, ‘OK, when am I gonna start taking the pills?’ There would be these suicide dress rehearsals. And if I went along with them, we got through the day.”

John no longer answered to anyone but Ann; anxious e-mails from his parents were ignored. Refuge employees hadn’t seen him in weeks, except for one or two long-distance glimpses of “Don John” carrying Ann from room to room. “Gently,” one of the guards recalls. “Like carrying a sick child.”

John’s life was playing out in an erstwhile dream home now patrolled by no fewer than nine armed guards who were forbidden even to enter it. His personal arsenal included two licensed Ruger pistols and two illegally acquired AK-47’s.

Ann says John was convinced that the water in the area could cure her. He also set up his own treatment regimen: an unknown concoction administered daily by injection.

“He was psychotic,” Ann says. “He started experimenting with me. He was injecting me with certain things. And I allowed this to happen.” She shrugs. “Yeah, I know,” she says. “But there was nothing non-intense about John’s and my relationship.”

The day Ann described the fatal shooting was our fifth together. We’d spent the previous four talking around the subject. She seemed like somebody trying to crawl out of the rabbit hole with a flashlight.

When zero hour arrived, on a muggy Thursday afternoon, her manner was one of resigned acquiescence. “Will it drive you berserk if I smoke?” she asked, pointing to a pack of Dunhills. It was the first time I’d seen her with a cigarette. She perched on the windowsill for 90 minutes, like a little bird, and took us back to sundown of January 7, 2010.

“After we did our sunset thing, we played Fallout 3,” she said. The video game, which John played obsessively, is part of an action series whose central character roams a post-apocalyptic wasteland in search of his missing father. “We would play for two or three hours.… When John said, ‘I’m ready for bed,’ I’d think, ‘OK, got through another day.’ So we go upstairs to our bedroom on the fourth floor.

“John was talking. He was saying some things. I don’t remember exactly what he was saying.… He had a routine ritual. He had to have his pillows arranged a particular way. I was already in bed. I was falling asleep, kind of in and out, and I heard him say something like, ‘You don’t know how it feels to wake up with your spouse half dead next to you.’ I opened my eyes and I saw—and once one has seen it, you know what it is—those two little dots that are the sight of the gun. The glow. And I realized that he had one of the handguns in his hands. And he was lying back on the pillows. And he had the gun pointed at his face as he was talking.

"She knew why she was in the hospital but was not aware of it. She knew, Yes, my husband died. But that was it—with no emotion whatsoever.”

“When I saw the gun I was stunned, and my immediate reaction was to get up on my knees and try to reach for it,” she went on. “The gun was loaded and cocked. I reached for the gun with both hands, and I was up on my knees. And I did put my hands on the gun. And the gun slipped through my hands. And it went off.”

Ann said she ran around to John’s side of the bed, saw blood dripping to the floor, picked up a two-way radio to call for help, and turned on a light. “I think I was in shock, because I was running around—which, given the state I was in, I shouldn’t have been able to do. But I remember I did, like, four laps around the bed as I was waiting for somebody to come up and help me. At this point, I already knew he was dead, because I’d heard that death rattle—that last breath.”

At 12:15 A.M., a guard with an estate security team known as Imperial Park heard a gunshot echo from the upper part of the house. Then he heard a woman’s voice crackle over his radio: “Post Five. Help! Help! Help!”

The guard, Moises Calderon, radioed his supervisor, Osvaldo Aguilar. Five frantic minutes elapsed before Ann and Aguilar were able to give Aguilar access to the secure private elevator. Once he reached the bedroom, Aguilar found Ann kneeling, splattered in blood, and stroking her dead husband’s hand. Near her on the floor lay one of John’s semi-automatic pistols: a 9x19mm Ruger P95.

Aguilar took Ann down to the second floor, where she popped a tranquilizer, sat at her laptop, and e-mailed her parents. Then she called her older brother, Ken Patton IV, at his home in Michigan. Ann’s first words to him: “He finally did it.”

From this point on witness accounts diverge. Ann’s team of lawyers and supporters describe a chaotic scene in which rubber-necking cops were texting snapshots to friends, swiping sunglasses and iPods, and grinning at her. Photos of the crime scene do show quite a crowd, but the prosecution insists everything was done by the book.

By 11 A.M., Ann was an hour inland, in a police station in the nearby city of San Isidro de General. There, she willingly gave investigators a witness statement and phoned Dr. Arturo Lizano, her psychiatrist in San José. “I need you to admit me,” Ann said in a whisper. “My husband just shot himself.”

That night at the hospital, both Lizano and Ann’s attending physician, Dr. Hugo Villegas, were stunned by what they saw. “It was amazing how thin, pale, and weak she was,” Lizano recalls. “She didn’t have the strength to hold a cup of coffee.”

She weighed about 80 pounds. The blood clot near her heart would require the installation of a permanent stent. Her skin was covered with open boils, welts, and infections. Most of the sores turned out to be needle marks from the injections John gave her.

“She was literally blank,” Villegas says. “She had no recollection of what was going on, and she basically was unable to fathom what was going to happen tomorrow. She knew why she was in the hospital but was not aware of it. She knew, Yes, my husband died. But that was it—with no emotion whatsoever.”

The status quo held for more than three months. Finally, Villegas says, “it started hitting her: My husband died. She became a lot clearer about what happened and what the consequences were. Of course, that generated its own levels of anxiety and despair.”

Gradually, Ann came out of it. She called Celine Bouchacourt, an old friend from Switzerland she hadn’t seen since the 1990s. “John was her whole world,” Bouchacourt says. “Ann told me, ‘I didn’t forget about you. I didn’t forget about other people. It was John. He wanted just me. And I felt that was what I had to give him.’”

Folie à deux. That was Dr. Lizano’s assessment. John and Ann had dissolved into a state of shared psychosis. At a certain point, one person’s delusions fed the other’s, and vice versa. Madness by osmosis.

When Ann finally walked out of the hospital after six months, she couldn’t go back to Boracayan, which was now a ghost house: the police had confiscated nearly all the Benders’ belongings. Beyond that, Ann’s two attorneys assured her that she could not be charged because of her inimputabilidad, which basically means mental incapacity. At no point, it seemed, did her lawyers claim she was innocent.

Alarmed by this, Ann turned to the man who had hired the lawyers on her behalf: Juan Alvarez, John’s handpicked trustee, who assured Ann that everything would be taken care of. He said the same thing right up until August 2011, when Ann was arrested and then charged with first-degree murder.

And there it was. The prosecution’s not-so-secret theory about motive was a noir classic: the lady wanted the jewels.

When this happened, Ann found herself at Alvarez’s mercy. He severely restricted the flow of money to both Ann and the refuge, and security cutbacks allowed poachers to return. Alvarez justified his actions by pointing to a postnuptial agreement between John and Ann. The gist of it was that Ann had waived her right to John’s property, and so Alvarez controlled everything on behalf of the refuge. Ann, however, believed that the postnuptial agreement was invalidated when they created the trust.

But then, in the months that followed, Ann caught a couple of breaks. One came in the person of Milton Jimenez, a former accountant at Alvarez’s law firm. Jimenez was so distraught about Ann’s plight that he quit his job and opened the firm’s books to her. He alleged—both to me and in sworn court depositions—that Alvarez had bilked the trust for millions, which he used to finance a lavish lifestyle and grand real estate ventures, including a high-end equestrian center in northern Costa Rica. Alvarez had done so, Jimenez alleged, by exploiting the Benders’ trust. “He believed that he was the sole heir and owner of the trust,” Jimenez said in a deposition.

The second break came during a chance encounter with an attorney named Fabio Oconitrillo, who had just quit the biggest criminal-defense firm in San José and was looking to start his own practice. “I just have to ask you one question,” Oconitrillo said when he spoke with Ann. “Did you at any point confess to shooting John?”

“No,” she said. Oconitrillo told her to plead not guilty and started preparing a defense.

Leading the case against Ann was an enigmatic, middle-aged county prosecutor named Luis Oses. Laconic and cagey, with a prominent forehead and close-set eyes, Oses relished his street-fighter vibe. “There is very little I can talk about,” he told me when we met in his office last October.

One thing he readily acknowledged: Ann had been under suspicion since the beginning. Within 72 hours of the shooting, Oses was reviewing forensic and police evaluations that cast doubt on her story. “One week after the death,” Oses said, “we had sufficient evidence to consider it not a suicide but a murder.”

According to the indictment, blood-pattern tests showed that the crime scene had been staged postmortem, forensic evidence indicated that the victim had been asleep when shot, and both the murder weapon and a spent shell casing had been found in incriminating locations. Firing a pistol nearly always leaves gun residue on the shooter’s hand, and John’s hands had tested negative for any trace.

Costa Rica eschews the jury system in favor of judicial tribunals composed of a chief justice and two associate judges. Verdicts need not be unanimous. The majority rules.

But at the heart of the case was the question of why a suicidal man would somehow shoot himself in the back of his head. The entry wound was located to the right of John’s cortex, in the right inferior occipital region of his brain—which means the bullet came from the back and right. John was left-handed. Ann slept to his right. Ergo.

The indictment offered no theory about motive, but in Costa Rica as in the U.S., prosecutors are not required to establish one. Still, a failure to offer a motive tends to reduce the chance of a conviction, so it seemed likely they would come up with something.

Oses wouldn’t discuss this with me, but his smile said plenty. “What I can tell you is that this case is basically divided,” he said. “The murder litigation is taking place here. All the litigation concerning the precious stones that were found on the defendant’s property—that case is being litigated in a separate court in San José.”

And there it was. The prosecution’s not-so-secret theory about motive was a noir classic: the lady wanted the jewels.

On the morning after John’s death, investigators found more than 3,000 gems inside the home: diamonds, rubies, opals. Some lay neatly arranged in custom-made display cases; others sat randomly on counters or were stuffed inside backpacks. According to prosecutors, most had been brought into the country illegally: no receipts, no duties paid.

Ann told me that everything had been legally acquired and that she was working on providing all the paperwork. But for the prosecution, an implied narrative began to form. The Wall Street bubble bursts in 2008. The Benders, facing liquidity problems, hit upon a cash business big on profits and short on tax oversight. But then the femme fatale kills her poor dupe to make off with the loot.

“That’s me,” Ann said sarcastically the day after I met Oses, “a criminal mastermind.”

She showed me a series of photos that police took while cataloging the jewelry collection. The gems included a red diamond (which the Benders bought in a $2.2 million lot with other jewels) and boxes of opals and diamonds worth $8.5 million. “The reason I bring this up,” Ann said, “is how do you make this work with this theory that I killed my husband to be able to run away?” She tapped the images. “This is $15 million,” she said. “I left them. Right on the counter.”

The trial, conducted in Spanish, began on January 14, 2013, in the eggshell blue court-house that sits in the center of San Isidro. Team Ann had driven down from San José the previous afternoon, in a guarded caravan that included two of Ann’s visiting relatives (her brother, Ken, and their grandmother, Ann Esworthy), her two closest friends (Celine Bouchacourt and Greg Fischer, a burly American she’d met in San José), and two friends of John’s from the U.S., Pete Delisi and Brad Glassman. John’s parents, unable to attend, sent the court statements that were supportive of Ann.

“Until now I hadn’t seen John or Ann in a decade,” Delisi said.

“Same for all their friends,” Glassman said.

Looking weak, Ann leaned on a cane as the group descended the steps of a sunken courtroom the size of a high school chemistry lab. Criminal trials in Costa Rica proceed much as they do in the U.S. One big difference: Costa Rica eschews the jury system in favor of judicial tribunals composed of a chief justice and two associate judges. Verdicts need not be unanimous. The majority rules.

The chief judge in Ann’s trial was José Luis Delgado, a square-jawed alpha male who presided with breezy authority. The two other judges scarcely said a word during the trial, which lasted six days and opened with a whiff of class warfare.

On one side was Fabio Oconitrillo, the immaculate private defender wearing an Italian-cut suit and flanked by an attractive young paralegalista carrying a zebra-skin bag and a white iPhone. Before them was a stack of case materials, neatly codified and color-coded.

“You don’t kill your husband because ‘Today I’m feeling bad,’ ” Oconitrillo said. “There is no motivation, and with no motivation there is no homicide.

Opposite them was Luis Oses, the lunchbucket civil servant wearing Dockers and a cheap dress shirt. Oses worked alone; on his table sat the single dog-eared case file he carried in an old backpack. While Oconitrillo addressed the court, he slumped in his chair, gazing blankly at points unknown.

Criminal defendants in Costa Rica are permitted to address the court during trial, and Ann spent more than an hour describing the life and death of her marriage. Her story was consistent with what she’d told me—except for the addition of one anecdote that served to illustrate the depths of John’s self-destructiveness. Two months before John died, Ann said, she’d thwarted his attempt to kill himself by jumping off their open-air elevator. This was news to me.

Ann, having waived her right to remain silent, submitted to questioning. But Oses seemed indifferent to the defendant; Ann, in turn, tended to supply one-word answers. Finally, they were interrupted by Judge Delgado, who asked Ann: “Did [John] give you reasons why he wanted to commit suicide?”

“He told me that he was not a good person, that he had failed to cure me,” Ann replied. “He told me he was tired of living a very hard life with everything he was facing. And he also told me that he was scared that he could harm somebody and that he was sure I would be safer without him.”

That night, with everybody eager to relax after a long day in court, Ann threw on a sparkly green dress and hosted a dinner at an outdoor restaurant specializing in chimichurri and sushi. The mood was reserved euphoria, thanks to a sense that the prosecution was weak. Someone reminded Oconitrillo of a moment earlier in the day when Oses had questioned the veracity of one of his own witnesses. “Just terrible,” Oconitrillo said. “But don’t tell him I said that.”

The twice-divorced Oconitrillo was wearing a pink Izod polo shirt and tight jeans. His paralegalista, now dressed in evening wear, nodded obligingly while he reassured Ann about Judge Delgado. “I know how he works,” Oconitrillo said. “If he’d been skeptical of your testimony, he would have thrown fifty questions at you.”

The relief seemed to make Ann woozy. So in stepped her friend Greg, a former bodybuilder who handled her like a China doll. I was struck with the realization that the friend was actually the boyfriend. During all the time I’d spent with Ann, hashing over the deepest intimacies of her life, she’d never mentioned anything about a relationship. Instead, she described her life as being “almost always alone and isolated.”

Late that night, I expressed bafflement to my translator, Ernesto, a San José hipster wearing oversize Prada glasses. “Accept that you can only know so much,” he said.

For the next three days, everything about the trial—the lawyering, the forensic work—seemed haphazard and baffling.

The best example was one of the prosecution’s key witnesses, Dr. Gretchen Flores, a government pathologist who examined Ann after the shooting. Flores was there to prove that John couldn’t have fired the fatal gunshot with his left hand. She made a compelling case, but only up to a point. Ann had repeatedly explained that, during the struggle for the gun, she’d jerked John’s hands toward the right side of his head, at which point the gun discharged. Oconitrillo offered witnesses who testified that John handled guns ambidextrously. He asked the doctor if she’d factored this into her findings. “It would require research,” Flores replied, “since that is a very different condition.”

Meanwhile, evidence of John’s self-destructiveness was everywhere. On the witness stand, Pete Delisi referenced three different times when John had confessed his suicidal urges, usually spurred by his inability to handle disappointment or failure. “Both my and his family knew his condition,” Delisi said. “And we knew it was a matter of time until this moment would come.”

At lunchtime I found Ernesto in the lobby having coffee with Oses. “The lady is going away for a very long time,” Oses told Ernesto. When Ernesto challenged him, Oses smiled and said, “Just wait till Friday.”

He placed a hand on Ernesto’s shoulder. “I don’t necessarily think the defendant is an evil woman,” he said. “I think maybe it’s possible to love someone too much.”

On Friday, the last day of testimony, Oses began by recalling two experts he’d questioned earlier. The first was Luis Aguilar, an investigator for Costa Rica’s top federal forensic unit. A placid giant, Aguilar served as ice to Oses’s fire while they analyzed a series of grisly death-scene photographs. These were projected onto a large video screen. Ann couldn’t look. One of John’s friends nearly passed out.

There, on the left side of his bed, lay the nude, blood-stained body of John Bender. His head was tilted to the left. In the back of his head, on the right, was the fatal wound. His left wrist dangled off the left side of the bed. Beneath his left arm was a river of blood snaking down the side of the mattress. Beside the pool of blood on the floor lay John’s pistol—a sight that made no sense given the location of the wound. We also saw images of the spent bullet casing, which lay behind the bed: closer to Ann’s side than John’s.

Next came Dr. Flores, the pathologist caught in the middle of the left-versus-right controversy. She, like Aguilar, contended that blood patterns on and around John’s body were inconsistent with a self-inflicted gunshot. The same went for the positioning of John’s body. “It shows no sign of struggling,” Flores said, “and is consistent with what we characterize as a body in rest.”

Finally, Flores discussed the significance of John’s right hand, which was shown to be lying flat on a pillow tucked down by John’s right waist. It was a given, she said, that John’s vital functions had ceased the instant the bullet entered his brain. “It is very difficult, anatomically, to shoot in that position,” Flores said. Even if John had done so, she said, his arm would have immediately fallen “en estadio inert.”

“Is it possible to shoot with the right hand and end with the position in which it was found?” Oses asked.

“In my experience,” Flores said, “it is not possible.”

Oses, during his two-hour closing argument, prowled and paced, staring straight at Ann. “She had the mental ability to turn the lights on,” he said. “After that she called on her radio. Then she was able to unlock the elevator mechanism. She was also able to come downstairs and was even capable of turning on the computer and sending e-mails.”

During the 60-plus minutes before the authorities arrived at the scene, Oses said, Ann and her security team had plenty of time to wash her hands and move the gun. He held up the murder weapon and crouched, as if he were on the right side of the Benders’ bed. “Our theory,” Oses said, “is that Ms. Ann got close and, holding the gun sideways, fired at her husband.”

He pulled the trigger: the click was loud enough to make Ann flinch. Then he gestured toward the back of the imaginary bed, where the shell casing was found.

He displayed the gun and said, “I have no approved gun permit and can, with no experience whatsoever, feed it and shoot it.”

He cocked and pulled the trigger. Easily. Repeatedly.

Oses closed by reminding the court that the only Bender who tested positive for gunpowder residue was Ann. “The version of events given by Ms. Ann is false,” he said. “It was Ms. Ann who shot the gun. That’s why her clothes had gunpowder on them. And the elements of the crime scene prove that John Felix Bender did not shoot himself. Considering that she ended the life of her husband in what the penal code defines as a cruel manner, we ask for 25 years in prison.”

Oconitrillo rose to Ann’s defense. “There is not a single piece of criminalistics evidence from which we can conclude, 100 percent, that my client committed homicide,” he began.

He tried to rebut many of the prosecutor’s assertions. For one thing, there was ample evidence that both the crime scene and the body had been disturbed during the chaos that followed Bender’s death. The crime-scene photos, it turned out, had been taken hours after investigators first found John’s body. And of course Ann’s clothes revealed traces of gunpowder—she’d been lying beside John when the gun went off.

“You don’t kill your husband because ‘Today I’m feeling bad,’ ” Oconitrillo said. “There is no motivation, and with no motivation there is no homicide.… Were they eccentric? Yes. It’s not a crime. Were they millionaires? Not a crime, either. They lived in a four-story castle? Again, not a crime.”

The final words came from Ann, who struggled to hold herself together as she blinked up at the tribunal. “I’m innocent,” she said. “I did not kill John. Since this trial began, on Monday, is the first time in three years that I feel I have rights. It’s been three years of hell. And I feel listened to and protected by the justice system. And I would like to thank you.”

After she finished, Judge Delgado announced that the tribunal would wait until Monday to render its verdict.

On Monday, Team Ann reconvened outside the courtroom—only to be informed that the judges needed a few more hours. Everybody slouched back to the hotel to kill time in the lobby, too spooked and exhausted to manufacture small talk. While I feigned interest in e-mails, I felt a presence materialize beside me. It was Ann.

“Last night I was lying in bed,” she said. “And I was thinking, What would I have done if I’d been in the prosecutor’s position? I would have said, ‘She’s crazy, something set her off, and boom! She killed him in a fit of craziness.’ But no. He goes for the whole enchilada. Which is really crazy.”

Then, just as quickly, she was gone.

An hour later, at the courthouse, a line of spectators snaked through the lobby and out to the street. In court, Ann was a trembling mess as TV cameras trained on her face. Oses didn’t show up, and Judge Delgado deferred to one of his colleagues, Francisco Sanchez. “Based on the evidence presented,” Sanchez said, “we have unanimously decided the defendant is acquitted.”

With good reason, I thought, the tribunal found the prosecution’s case short on evidence, long on conjecture, and devoid of motive. The forensic analysis, Sanchez said, was based on a series of flawed or outright false assumptions.

But then, unbidden, Judge Delgado interrupted. “The tribunal does not count with certainty the criminal responsibility of the defendant,” he said. “We found it possible that the defendant could have killed her husband, but also possible that it could have been a suicide. By not being certain, the tribunal found that the evidence is not conclusive as used by the D.A.”

If the caveat bothered Ann, she didn’t show it. She was too busy hugging her team, ducking cameramen, fumbling for a cigarette, and getting the hell out of San Isidro.

Two hours later, at a roadside diner halfway to San José, I saw her for the last time. She was exhausted; her hands trembled.

“You OK?” I asked. She started to reply, but no words came out.

I left the next morning, relieved to see the drama end. Ann’s counteroffensive against her trustee, Juan Alvarez, proceeded apace. Authorities had raided his office, and a judge had replaced him with an interim trustee who was tasked with determining how much money (if any) remained in the trust. Ann seemed to be headed for a better life, probably in Florida.

And yet.

Soon came news that the jewelry-smuggling case had gone from dormant to active. Also, on February 12, a Costa Rican TV news outlet reported that prosecutors were investigating whether Ann’s trial was influenced by a past business deal between her attorney and one of the judges who acquitted her. In 2003, Oconitrillo had notarized the sale of a parcel of land to none other than Judge Delgado. In response, Oconitrillo said that a ten-year-old transaction in no way suggested the sort of “close friendship” forbidden by law. Delgado had no comment.

But the biggest twist came when prosecutors announced they would appeal the acquittal. In Costa Rica, prosecutors can complain to a higher court, which may either dismiss the appeal or order a new trial. Although the latter happens only rarely, Ann can’t leave the country until the appeal plays out—a process that could take six months to a year.

On March 14, Ann sent me an e-mail that read, in part:

“I’ve reached the point where I can’t accept on a fundamental level what has happened. Everything I suspected has borne out to be true in the evidence. I can’t sit here, a prisoner for an indefinite period of time, and not fight on all fronts. I’m willing to do anything to expedite ending this.

“The story is far from over,” she concluded. “Nothing is over. Nothing.”

Ned Zeman is a contributing editor at Vanity Fair.