Prosecutors believe the head-on train crash in southern Germany last week which killed 11 people was caused by "human error" by the train dispatcher.
Dozens of people were also injured when two commuter trains slammed into each other on a single-line track near Bad Aibling, 40 miles south-east of Munich.
Chief prosecutor Wolfgang Giese says his office has opened a criminal investigation against the 39-year-old dispatcher.
Mr Giese said today that according to investigators "had he (the dispatcher) behaved according to the rules, the trains would not have collided."