The person arrested following the deadly stabbing in Solingen is a 15-year-old, according to the investigating authorities on Saturday.
The authorities are investigating whether the teenager is connected with the attack that left three dead late on Friday night.
The police are weighing whether to potentially charge the teenager with a failure to report planned crimes.
“According to witness statements, an unknown person allegedly spoke with the teenager shortly before the attack about intentions that would match the execution of the crime,” said senior public prosecutor Markus Caspers.
The investigators said they do not yet know whether the person is the perpetrator.
The eyewitnesses to the conversation did not observe the crime itself. So far, police have not yet identified a perpetrator.