Thousands of people, including top Polish and European officials, have turned out for the funeral of Pawel Adamowicz, the slain mayor of the northern city of Gdansk.
Adamowicz died on January 14 after being stabbed the night before at a charity event in the Baltic port city.
The arrested suspect is an ex-convict with a grudge against an opposition party that Adamowicz once belonged to.
Among those attending the burial at St. Mary’s Basilica were European Council President Donald Tusk, a personal friend of Adamowicz. Poland's President Andrzej Duda and Prime Minister Mateusz Morawiecki also attended along with former leaders including Lech Walesa.
Other dignitaries included former German President Joachim Gauck and city mayors from other countries. The powerful leader of Poland's ruling conservative party, Jaroslaw Kaczynski, was not present.
The slaying comes with Poland largely divided over actions by the conservative ruling Law and Justice party.
It has triggered calls for greater national unity and condemnation of hate speech in the public sphere.