“They do not feel sorry; they are sowers of hatred,” Mr. Szczepaniak said. “We hope very much that after this murderous murder, the Polish nation will finally understand which side the truth is on. And again we can be proud of Poland and our solidarity, as we were in 1989.”

That was the year Poland broke free from communist rule. The spark in the fight for freedom came from this city, where the labor unions of the shipyards banded together in a movement that became known as Solidarity, or Solidarnosc in Polish.

But the roots of today’s current political divide can also be found in those days of uprising.

Mr. Kaczynski, along with his twin brother, Lech, fought alongside Lech Walesa to bring down Communism. In 1990, he helped the Solidarity hero win the presidency and later served as Mr. Walesa’s chief of staff. But they fell out after an intense power struggle and have been enemies ever since.

Mr. Kaczynski soon came to believe that the revolution had never been completed. By agreeing to a bloodless transition that allowed some Communist figures to remain in public life, he believed political leaders had failed to eradicate the Soviet infection.

He formed Center Agreement and, ultimately, Law and Justice, which had a brief turn in power from 2005 until 2007. But much of his agenda had been stymied by the courts. The party lost the early election to the liberal Civic Platform.