Four people were injured in the attack on a high-speed train in November.
The prime suspect in a knife attack on board a German train had an Islamic extremist motive, prosecutors have said.
Four people were injured during the attack on a high-speed train between Passau and Hamburg in November.
Authorities initially said that the man attacked his victims apparently at random and was placed in a psychiatric centre after his arrest. Later, Munich prosecutors stated they were no longer ruling out an Islamic extremist motive.
On Monday, the prosecutor's office said that there were “weighty indications” that the suspect’s actions were based on support for the ideology of the so-called Islamic State group.
But authorities said there was no evidence so far that he was involved with or “directed” by the group.
Police had said that the suspect -- a 27-year-old Syrian citizen living in Passau -- came to Germany in 2014 and was granted asylum in 2016.
The investigation has now been taken over by the Federal Prosecutor's Office in Karlsruhe, which is responsible for terrorism and national security.