Stifling heat envelops Ari Kaplan and his son Avi, 9, as they stroll hand-in-hand down Baltimore’s Pratt Street one Sunday morning, in the direction of Camden Yards. Ari, a mathematics expert, is a consultant for the Baltimore Orioles. The laptop computer hanging from his left shoulder contains key analytics, “sabermetrics,” in baseball parlance, that help quantify players’ capabilities and recognize patterns that might help the team win games.Even among sabermetricians, Kaplan flies under the radar. He arrived a decade-plus after Bill James in the late 1970s began publishing groundbreaking numerical analyses of ballplayers. He isn’t famous like Oakland Athletics executive Billy Beane, the sabermetrics convert and subject of the Michael Lewis book and the Brad Pitt film Moneyball.But Kaplan, 47, is respected throughout Major League Baseball for devising key measurements and innovative software that front-office personnel, scouts, managers, coaches, and players use, going back to when he was a California Institute of Technology student measuring the effectiveness of relief pitchers entering tough situations. Upon buying the Chicago Cubs in 2009, Tom Ricketts hired Kaplan to help pursue Theo Epstein as general manager, establish the team’s analytics department, and “think through questions from a technical, quantitative perspective,” he said; seven years later, the Cubs broke a 108-year drought by winning the 2016 World Series. “He’s a very, very smart man who understands the game,” Ricketts says of Kaplan. His business partner, ex-Los Angeles Dodgers general manager Fred Claire, says he considers Kaplan a baseball “pioneer.” An Orioles colleague in 1990 and current Seattle Mariners executive, Lee MacPhail IV, calls Kaplan “the harbinger of the analytical side of the game” who “was processing the world at a different level.”But few in MLB know of Kaplan’s other calculations, which share space with the baseball analytics on his laptop. Those are the numbers he’s crunched for two decades trying to solve what he calls “the greatest mystery of the 20th century”: What really happened to Raoul Wallenberg, the Swedish diplomat who led one of the most extensive and successful efforts to rescue Jews during the Nazi era, and disappeared during the Red Army’s Siege of Budapest in January 1945?***Growing up in Lawrenceville, N.J., Kaplan wasn’t into baseball. That changed in 1985 when his older brother Todd kept switching the family’s television to a New York Mets game. An exasperated 14-year-old Ari snapped.“Just leave it on one station,” he ordered Todd.“I got addicted right away,” Kaplan says. Mets slugger Gary Carter became his favorite player.Kaplan’s interest in the fate of Raoul Wallenberg also started at home. His mother, Eva, belonged to an organization that was lobbying Congress to press the Soviet Union to come clean about Wallenberg’s whereabouts.A Swedish businessman and a Christian, Wallenberg was recruited by the Roosevelt administration’s War Refugee Board for a belated mission: Save Hungarian Jews from the Nazis. Posted as a diplomat to Sweden’s embassy in Budapest, Wallenberg rescued Jews during his six months there, beginning in July 1944. Precisely how many people Wallenberg saved is unknown. Rob Rozett, an expert at Yad Vashem, Israel’s renowned Holocaust-commemoration museum, says that Wallenberg officially issued 7,800 schutzpasses, certificates of protection, but likely rescued “many more.”One was Vera Goodkin, a neighbor of the Kaplans. At the age of 14, she and 25 other youth had lived in an orphanage on the Pest side of the Danube River to which Wallenberg and his staff evacuated them. The orphanage was among 32 Budapest buildings he rented as “safe houses,” under diplomatic immunity from Hungarian authorities—the fascist Iron Cross party overthrew the government in October 1944—and from their boss, Nazi Lt.-Col. Adolf Eichmann.Wallenberg often visited the orphanage in late afternoon. Goodkin recalls him clowning around with the children, sharing sweets, hugging lovingly. Then, he’d depart for wherever he’d sleep that night to evade harm, even assassination. Goodkin “knew that his name was Raoul,” but says she “had no idea” of his role in rescuing Hungarian Jews and foreigners—Goodkin and her parents, Emil and Margit Herman, also Wallenberg rescuees, were Czechoslovakian—who’d reached Budapest before the Nazi claws clamped shut on Hungary, the last occupied country.“He was an angel without visible wings,” she says.Goodkin remembers the preteen Ari accompanying his mother to the group’s meetings. He was skinny, had curly hair, dressed well and was by far the youngest person attending.“He soaked it all up,” Goodkin, 87, says.Kaplan knew several Wallenberg survivors. He biked by their houses to fling each day’s edition of The Times of Trenton and knocked on their doors to collect subscription payments. They addressed his synagogue and high school. Goodkin and her husband came over for dinner.“It was very inspirational, that someone would risk their life,” Kaplan remembers. “You looked at the Nazis as indestructible, but here was someone who stood up to them and rescued people who lived very close to me,” he says.***Raoul Wallenberg “is one of the biggest heroes in the history of the world,” Kaplan states. “I liken him to Martin Luther King Jr., John Lennon, Gandhi.”We’re sitting in the stadium suite of Orioles Vice President for Baseball Operations Dan Duquette, who, as the Montreal Expos’ general manager, hired Kaplan as a consultant in 1992 for his analytics acumen and brought him back to the Orioles in 2013. Heavy rain douses the field below, delaying the start of a game against the Houston Astros. Avi fiddles with his smartphone.Kaplan joined the Wallenberg cause in 1995, when Eva’s friend in New York, Agnes Adachi, who’d been Wallenberg’s secretary in Budapest, mentioned Susan Mesinai, a consultant to the Swedish-Russian Working Group on the Fate of Raoul Wallenberg, who was collaborating with the University of Chicago biochemist Marvin Makinen. Incarcerated in Russia’s Vladimir Prison on charges of espionage in the early 1960s, Makinen had heard Wallenberg’s name mentioned as someone who had previously been imprisoned there.Mesinai and Makinen needed an expert in analytics and building databases to assemble information related to Wallenberg sightings in Russia post-July 17, 1947, the date the Soviets claimed (in a 1956 report to Sweden) that he had died of a heart attack in Moscow’s Lubyanka Prison. Eva volunteered her son, who had just moved to Chicago to work for Oracle on a project for the U.S. Department of Veterans Affairs while simultaneously consulting for several MLB teams. In Kaplan, Makinen says, “I was most fortunate to find someone who could help solve this.”Kaplan’s strategy was to digitally organize the data related to Wallenberg’s presumed imprisonment, then analyze them, seeking relationships between eyewitnesses and cellmates. Patterns would reveal clues, producing facts, yielding truth.“It was the same concept [as in baseball]: Making something that used to be done by hand automated,” he explains. While millions of pitches by major- and minor-leaguers are charted each season, “with Wallenberg we have ‘sparse data’—a lot less information—so how do you find the patterns?” he says. “In prison, the geography seemed very meaningful. …“In baseball, it’d be: Show me who are the third basemen in the Mets’ system. With Wallenberg: Show me two people who were his cellmates; show me who was across the hall who could have been knocking in code.” Kaplan calls that “interrogating the database” to trigger further questions—and answers.To illustrate his point, Kaplan opens his laptop to a slide depicting the third floor of Vladimir’s Korpus (building) 2. Two years before Kaplan’s arrival, Makinen had interviewed Varvara Ivanovina Larina at Vladimir, 120 miles east of Moscow. Larina, a prison employee, mentioned a non-German European who, decades earlier, was kept in solitary confinement. The man complained about receiving cold food, so Larina’s bosses ordered her to serve his meals first. To Makinen, the man must’ve merited special status. A commoner’s gripes wouldn’t be tolerated. That order occurred, Larina had noted, around when a prisoner named Kirill Ivanovich Osmak died. The foreigner, she remembered, resided across the corridor from cell 2-49, Osmak’s cell.The revelations were gold. So was Larina’s identifying an unpublished photograph of Wallenberg as the foreigner.Makinen prevailed upon Russian authorities—the USSR fell in 1991—to allow access to prisoners’ records. Makinen sought to prove that Wallenberg was the prisoner Larina remembered when Osmak died on May 16, 1960. He wanted to know who occupied cells near the foreigner’s. That would open new conduits for information.In 1998, Kaplan flew with Makinen to Russia and digitally scanned cards spanning 1947 (the year Wallenberg supposedly died) to 1972 (the last Wallenberg sighting a freed prisoner mentioned), covering 8,049 Vladimir prisoners and about 100,000 prisoner shifts between cells. It was a massive undertaking, but just the start of their work. The duo analyzed the cards, learned what cells appeared unoccupied—which, in the crowded prison, meant the cards were removed to conceal those inmates’ identities—and detected patterns. No Wallenberg card turned up. Kaplan then built a database into which information pulled from the scanned records was painstakingly entered, checked and plotted into each diagramed prison cell.In all, the men made eight trips together to Moscow. Most included visits to Vladimir, 16-hour days analyzing the database in poorly lit and ventilated rooms under guards’ watch. The laptops on which they worked couldn’t be removed, so any new ideas they had in Chicago required awaiting the next trip to Vladimir, retrieving the laptops, and writing new software on-site. Their analysis revealed this about two cells opposite Osmak’s: cell 2-46 lay unoccupied for 274 consecutive days; cell 2-44, for 243 consecutive days.“Why did they move people out of the cells [adjacent to Wallenberg’s], all starting the day Osmak died?” Kaplan asks, pointing to the screen.Kaplan expected a breakthrough in September 2016, when he and Makinen visited Moscow to present officials with a 57-page report requesting specific documents, running from the Soviets’ wartime intelligence files on Wallenberg to papers dealing with the return in 1999 of Wallenberg’s personal items. Five Wallenberg relatives and two other members of the Chicagoans’ research team, known as The Independent Investigation Into Raoul Wallenberg’s Fate, also came to the castle-like building housing Russia’s Ministry of Information. Vasily Khristoforov, head of the documents and archives section of the Federal Security Service (formerly the KGB), accepted the report and promised to respond.In November, Khristoforov was fired by President Vladimir Putin. The move deflated the group. Receiving “just a handful” of the documents “would have solved the case or at least shed light,” Kaplan says. Wallenberg’s fate eventually “will be revealed,” he insists. “It is just a matter of when, and I want it to happen soon, for the closure of his family and those he rescued. That is what keeps me upbeat.”***You can help support Tablet’s unique brand of Jewish journalism. Click here to donate today.