WARSAW, Poland — As Poles mark the eighth anniversary Tuesday of a plane crash in Russia that killed President Lech Kaczynski and dozens of other top Polish officials, new monuments are going up and streets are being renamed to honor the victims of the national tragedy.

But there is also a more subtle change. Jaroslaw Kaczynski, the late president's brother and the country's most powerful leader, is quietly backing away from actively promoting a theory that it was Russia that brought the plane down.

For years, Kaczynski, leader of the ruling conservative party, has cast doubt on official investigations that ruled the crash an accident, and has vowed to discover the truth of what brought down the plane carrying 96 people near Smolensk, Russia, on April 10, 2010.

On the 10th day of each month since then, Kaczynski has attended memorial services for his beloved identical twin, his sister-in-law and the others who perished. He has also led fiery political rallies where he repeatedly vows to find the truth, warns of dangers to Poland and denounces his opponents.

This monthly ritual in Warsaw has also become a magnet for anti-government protests, and rising security costs to separate pro-government and anti-government demonstrators had itself drawn criticism.

In remarks published Friday, Kaczynski insisted he still puts the likelihood of an assassination at "99 percent," telling the right-wing monthly Uwazam Rze that "the only concept that explains everything is an assassination."

But there are other signs that Kaczynski is easing up on promoting the theory that Russia assassinated a Polish president who had denounced Russian actions during the Russia-Georgia war of 2008.

He says Tuesday's monthly rally will be the last because there will have now been 96 of them, one for each victim. Kaczynski, a Roman Catholic who wears black in public, says he will keep attending monthly religious services but that the commemorative role of the rallies will be taken over by a new monument in Warsaw.

Sociologist Jadwiga Staniszkis, who has known the 68-year-old Kaczynski for more than four decades, says he must have realized that no more political mileage can be had from the monthly rallies, and that they cannot change the fact that the brother to whom he was extremely attached is gone.

"He is deeply changed, he is tired, crushed, unwell and he is looking for a way to gently withdraw from it and do his own private mourning," Staniszkis told The Associated Press.

Kaczynski also conceded recently that the final report from a new investigation launched by his party to prove the assassination hypothesis will not be ready by the eighth anniversary, as planned.

And, significantly, the leading proponent of the Russia-ordered-assassination theory, Antoni Macierewicz, was removed from the post of defense minister job in January. Macierewicz opened a new investigation into the crash after Kaczynski's Law and Justice party won elections in 2015, seeking to prove his suspicions.

For Rafal Trzaskowski, a lawmaker with the opposition Civic Platform party, this theory is simply a "cynical political game." He said that while Kaczynski and Macierewicz kept saying they were "getting closer and closer to the truth," there was never any new information, while an "atmosphere of suspicion was being built through a myriad of absurd theories that disturb Poland's political life."

According to surveys, a majority of Poles believe the crash was an accident. It occurred during an attempted landing in heavy fog at a rudimentary and little-used Russian airport as the presidential delegation traveled to honor Polish officers murdered by the Soviet Union during World War II.

Some say that there is no final report because the assassination theory is false and no proof of it can be found.

"You cannot interminably deny facts and feed a conviction in your voters about things that did not take place and for which there is no material foundation, no proof," said Ewa Marciniak, a professor of political science at Warsaw University.

A new black stone memorial has gone up in Warsaw's central Pilsudski Square to the victims, and it will be unveiled Tuesday amid a day of commemorations. A major Warsaw thoroughfare was renamed Lech Kaczynski Street in recent days, as streets, squares and roundabouts across Poland are being named after the late president.

A memorial was even unveiled Friday in Budapest, the Hungarian capital, in a ceremony attended by Kaczynski and the prime ministers of both countries.

"I think Kaczynski has understood that the theory of the assassination cannot stand the test of time and he is looking for other forms of commemoration," Marciniak said.