At a demonstration to commemorate the racist attack in Hanau two years ago, in which nine people with foreign roots were murdered by a perpetrator, the police arrested a man in Frankfurt on Friday evening.
He had shown the Hitler salute and obviously wanted to provoke.
The man was not among the demonstrators, the police pointed out.
After his personal details were recorded, he was released.
After this incident, around 800 demonstrators moved peacefully from the Galluswarte to the main station in the city center, the police reported.
The demonstration was originally registered as a star march, but because of the heavy rain and strong wind on Friday evening, the other trains were canceled.
Two years ago on Saturday, a German born in 1977 shot dead nine people in and in front of a shisha bar, another bar and a kiosk in Hanau within a few minutes.
The assassin later shot his mother dead in her apartment and then himself. As it recently emerged, the assassin, who thought the AfD was not radical enough, was most likely suffering from a hard-to-detect type of schizophrenia.