WARSAW — For six weeks, Jaroslaw Kaczynski kept up the charade.
By day, he appeared at political rallies, campaigning in mourning clothes as a stand-in for his twin brother, Lech, who had been running for a new term as Poland’s president before he died in a shocking plane crash over the Russian city of Smolensk in 2010.
By night, he took off his black tie, went to the bedside of his ailing mother and told her lies. Lech was on a trip to Peru and Argentina. A volcanic eruption in Iceland had slowed his return. He even printed fake newspaper articles chronicling the fake journey, which a former associate saved and showed to The New York Times.
Only after Lech was buried and his mother had recovered did Jaroslaw Kaczynski tell her what had really happened.
“There were moments that I wanted to believe those stories myself,” Mr. Kaczynski said in a rare interview the year after the crash. “That Lech was alive.”
It is an aching testament to filial duty and sibling devotion, if also to dark personal obsession. Eight years later, Mr. Kaczynski is the dominant political figure in Poland, an enigmatic man operating mostly in the shadows. His Law and Justice party has eroded democratic freedoms and weakened the rule of law in Poland, while pushing the country into an increasingly acrimonious dispute with the European Union.
The confrontation between Warsaw and Brussels is another major challenge for a European Union already under siege from anti-establishment, populist parties across the Continent — partly because of Poland’s economic and military importance, partly because of the symbolic blow of seeing a country once synonymous with democratic yearning turn the opposite way.
It is also part of a broader pattern in Central and Eastern Europe, where Mr. Kaczynski has formed an alliance with Hungary and its populist leader, Victor Orban. Their nationalist rhetoric has found emulators in neighboring countries.
When Europe’s leaders gather in Brussels this month to discuss whether Poland should be penalized for changes to its judicial system that many experts say undermine the rule of law, other nations will be watching closely. Failure to take action, critics worry, may embolden nations like Slovakia and Romania that are flirting with their own brands of “illiberal democracy.”
What complicates the situation further is Mr. Kaczynski, and how he has blended the personal with the political. From the moment of his brother’s death, he has nurtured a mythology of martyrdom and aggrieved nationalism around the Smolensk crash, using the tragedy as a narrative to try to reshape Polish identity, even as two independent inquiries placed blame on bad weather and human error.
The government has opened a new investigation and hauled up political enemies for questioning — even as his party is tightening its grip on the judiciary. His critics say he is using Smolensk as a pretense to arrest political enemies before elections in 2020. Others wonder if he is simply gripped by anguish, vengeance and paranoia, and is dragging his country along with him.
Or, perhaps, it is both.
“It is impossible to overestimate the significance of the Smolensk crash in the life of Jaroslaw Kaczynski — and in the life of Polish politics in general,” said Marek Migalski, who ran for the European Parliament as a Law and Justice candidate in 2010 and is now a lecturer at the University of Silesia in Katowice. “For Kaczynski,” he added, “public debate is no longer a political one — between people of different values; it’s an eschatological war between good and evil.”
For years, Mr. Kaczynski’s party has pointed to a host of possible devious scenarios — a thermobaric bomb that blew up the plane without leaving evidence; assassins using artificial fog to obscure the runway. But the heart of the narrative boils down to two basic unproven accusations: The Russians did it, and Polish political opponents of Mr. Kaczynski deliberately conducted an inadequate investigation to cover up their own negligence.
For Mr. Kaczynski’s supporters, it has become an article of faith that the crash was no accident. Instead, it reinforces ancient realities: that Poland still faces a threat from Russia to the east and should remain wary of the great powers to the west that have betrayed Poland in the past. When the governing party declares that Poland’s sovereignty is under threat, the smoking plane wreckage in the Russian woods is considered proof.
A few weeks ago, tens of thousands of supporters gathered in Pilsudski Square in Warsaw to commemorate the eighth anniversary of the crash. A new monument to the 96 people killed in the crash was unveiled — a block of solid black granite, with 18 stairs carved into the stone, a symbol of both the stairs leading onto the plane and of a stairway to heaven.
The Law and Justice party has spent years trying to discredit the findings of the earlier inquiries and, since taking power, government prosecutors have ordered the remains of nearly all the victims of the crash exhumed — sometimes without even informing the families of the victims. As the anniversary approached, officials promised that they would present new evidence that would reveal the truth.
The anniversary came and went with no new details made public.
The faithful, however, remained unshaken.
“The Kaczynski model of political strategy, within his own party and for the country as a whole, has always been ruling through division and conflict,” said Marcin Buzanski, a senior adviser at the Casimir Pulaski Foundation, an independent, nonpartisan research institute.
During a heated session of Parliament last year, the depth of Mr. Kaczynski’s anger was captured on video.
“I know you’re afraid of the truth, but do not wipe your treacherous mugs with my late brother’s name,” he said, banging his hand on the podium. “You destroyed him! You murdered him! You are scoundrels!”
It was a rare public outburst from a man who apparently prefers to wield power from behind the scenes. He holds a seat in Parliament but is neither prime minister nor president. He does not use email, or carry his own mobile phone or wallet. He rarely holds anything resembling a news conference and gets most of his news filtered through aides.
He has never married, has no children and lives alone with his cat. Yet, as leader of the Law and Justice Party, his power is unquestioned. If he thinks a law needs to be passed, it is usually passed. His control is not total — there are factions even within his party that he must contend with — but it is sweeping, according to friends and foes alike.
For more than a month after Mr. Kaczynski went to the hospital to have knee surgery on May 5, much of the nation’s pressing business was conducted by his bedside. He recently left the hospital, but his prolonged absence from the public stage raised questions about the direction his party and country will take when he leaves.
For years, the one person who could persuade Mr. Kaczynski that he was veering off course was his twin brother, Lech. They had once starred together as child actors, appearing in a 1962 hit movie, “The Two Who Stole the Moon,” in which they played mischievous twins who set out to capture the gold moon and sell it.
Of the two, Lech grew to be the more outgoing, public figure, while Jaroslaw was regarded as brilliant but also mercurial, largely keeping his own counsel.
No one doubts Jaroslaw’s grief over his brother’s death. On the day of the crash, Lech Kaczynski was flying to visit a memorial in the Katyn Forest, a place haunted by history, killing grounds where more than 20,000 Poles were slaughtered by Red Army soldiers in the early days of World War II, a crime that the former Soviet Union long denied and outlawed Poles from discussing.
In the plane crash, Lech died along with the top ranks of the Polish military and members of Parliament.
But whether Mr. Kaczynski truly believes the conspiracy theories that he promotes is harder to know.
Joanna Kluzik-Rostkowska, who served as Mr. Kaczynski’s campaign manager in 2010, spent nearly every day with him immediately after the crash.
“The first thing he said to me, unasked, was: ‘Don’t think for even a second that I believe this business about it being an assassination,’” recalled Ms. Kluzik-Rostkowska, who is now aligned with the political opposition.
She says she does not know what he truly thinks anymore, even as the question has taken on far greater significance.
Mr. Migalski, another former ally, does not have a definitive answer either. “Does Jaroslaw really believe the Russians assassinated his twin brother?” he asked. “If he truly believes that, then Poland is in great danger. Because if there was a crime there must be a punishment.”
The government is moving to settle scores. Bronislaw Komorowski, who became acting president after the plane crash, was summoned to the prosecutor’s office the week of this year’s anniversary and asked about government negligence in the investigation.
Donald Tusk, who was Poland’s prime minister at the time of the crash, has been repeatedly summoned for questioning in two separate Smolensk investigations, most recently in the trial of his former chief of staff, Tomasz Arabski.
Mr. Arabski and four other government officials who played roles in organizing the trip are facing charges of negligence. If Mr. Arabski is convicted, it could pave the way for prosecuting Mr. Tusk, who is currently the president of the European Council, which represents the leaders of the European Union. Mr. Tusk is widely expected to be the main rival of Mr. Kaczynski’s party in the 2020 presidential elections in Poland.
“One of the reasons Kaczynski is so eager to commandeer the Polish judiciary may be that he wants to use it against Donald Tusk,” said Marcin Matczak, a law professor at Warsaw University.
Indeed, many say that Mr. Kaczynski is trying to use the Smolensk crash to reshape historical memory, placing his dead brother at the center of the country’s hard march to freedom, and himself as the guiding force leading it into its next chapter, what he calls the Fourth Republic.
Behind the conspiracy theories is a deeply held belief of Mr. Kaczynski’s that when Poland first emerged from Communist rule to form its Third Republic, it did not properly cast out all those who had helped the Communists keep their grip on power.
Those people, in his view, still infect the system.
That belief has fueled the growing battle between Mr. Kaczynski and the man widely hailed as the hero of the Solidarity movement, Lech Walesa, who has been a vocal critic of the mythologizing of Smolensk.
Mr. Walesa has posted messages on Facebook condemning the spread of Smolensk monuments, and he was going to take part in protests last summer at one of the monthly marches that were held to mark the crash.
But in response to growing demonstrations against the marches and the politicization of the tragedy, the government passed a law limiting where protesters could gather — a law widely criticized as undemocratic — and added hundreds of police officers to the route of future marches.
Mr. Kaczynski has become more strident in his accusations that Mr. Walesa, who was imprisoned for leading striking workers during the Solidarity movement, had ties to Communists.
He claims it was his twin brother, Lech Kaczynski — not Lech Walesa — who was the real leader of Solidarity.
For outside observers, the different views on Smolensk reveal how Poland, once a pillar and paragon in the defense of democracy, has become a land divided.
Graffiti in a bar in Warsaw summed up the debate: “Smolensk — lesson, tragedy, or the first Polish fake news.”