Germans will commemorate the first anniversary of the mass shooting in Hanau in which 10 people were killed.
Far-right extremist Tobias Rathjen, 43, went on a shooting rampage on February 19, 2020, in the town of Hanau, west of Frankfurt.
He killed nine people at two shisha bars popular among the Turkish community before returning to his apartment where he killed his mother and then committed suicide.
He published racist documents on his personal website before carrying out the attack.
German President Frank-Walter Steinmeier will lead a commemorative event gathering 50 people, scaled down owing to Covid-19 restrictions, in Hanau's Congress Park.
Demonstrations remembering the victims will be held in Berlin, Hamburg, Munich and across the country.
The investigation into the attack is still ongoing, with many questions unanswered and little known about the attacker.
Edgar Franke, the government commissioner for the victims of terrorism, pleaded this week for closure for the victims' friends and families.
"There can be no public criminal trial against a dead attacker in which the victims can ask questions. This makes it all the more important to fully clarify the background," he wrote on Twitter.
Rathjen lived with his parents in Hanau. He was a sports shooter and legally owned several weapons, but was not known to police.
In November 2019, however, he had filed a criminal complaint about a "secret service organisation" that he accused of "tapping into people's brains" in order to "control world events".
In 2002, he was found to suffer from paranoid schizophrenia, which apparently remained untreated.
Relatives of the victims lately focused their attention on Rathjen's father, who they believe was partly responsible for the crime.
They filed a 16-page criminal complaint against the 73-year-old, accusing him of being an accessory to murder, according to Sueddeutsche Zeitung newspaper.
They allege he had a controlling relationship with his son, knew about plans for the attack and encouraged it.
The families also criticised the police response on the night of the attack, saying the emergency number was busy and they could not get through.
So far, 42 family members of the victims have received about €1.2 million ($1.5 million) in compensation from the federal government, with more potentially in the pipeline, according to the Ministry of Justice.
Organisations across Germany called for decisive action against racism and right-wing extremism before the anniversary.
"For those affected, Hanau is potentially everywhere, all the time," said Atila Karaborklu, chairman of the TGD society for the Turkish community in Germany.
Right-wing extremism and racism are now taken more seriously at the political level, but are still not a high enough priority in Germany, he said.
Chancellor Angela Merkel noted the upcoming anniversary in her weekly podcast at the weekend, saying: "Racism is a poison. Hate is a poison."