In the case of a 75-year-old woman stabbed to death in Berlin Prenzlauer Berg, the suspect neighbor is to be admitted to a psychiatric facility.
The public prosecutor's office had reached the temporary placement, the authority announced on Sunday via Twitter.
The woman was stabbed to death in her apartment.
A 20-year-old neighbor was arrested as a suspect, the police said on Saturday.
A homicide squad is investigating.
According to previous knowledge, the young man is said to have broken into the neighbour's apartment in Oderbruchstrasse by force on Friday evening around 8:10 p.m.
There he is said to have stabbed the elderly woman with a knife.
An emergency doctor could only determine her death, said a fire department spokesman.
According to the police, the suspect initially fled.
A little later he returned to the scene and turned himself in to the police.
Witnesses had therefore alerted the emergency services.