According to the investigators, two days after the violent crime against two girls in Illerkirchberg near Ulm, a temporary suspect killed himself.
As reported by the public prosecutor and the police on Thursday, the 25-year-old from Eritrea was arrested and interrogated and was released a little later.
The authorities emphasized that there was no suspicion against him or another man.
The alleged attacker fled to the 25-year-old's apartment after the crime.
A 27-year-old - also Eritrean - is said to have attacked and seriously injured two girls on the way to school in Illerkirchberg near Ulm on Monday.
One of the victims later died in the hospital.
The autopsy showed that the 14-year-old bled to death after stab wounds.
The second girl, aged 13, was seriously injured.
The police found a knife on the 27-year-old, which investigators believe to be the murder weapon.
Arrest warrants for murder and attempted murder have been issued for the suspect.
The man was last injured in a correctional hospital.
Why he attacked the two students remained unclear.