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A signal controller at the center of an investigation into a German train crash that killed 11 people admitted on Tuesday to playing a game on his mobile phone while in charge of train traffic on that day, the public prosecutor's office said.

The man was detained on Tuesday after developments in the investigation into the head-on train collision in Bavaria in February, which was Germany's deadliest train crash since 1998.

The prosecutor's office in Traunstein, near the border with Austria, said in a statement that the latest investigation shows that the suspect violated train traffic regulations as his “mobile telephone was switched on in the morning hours of the disaster, an online computer game had been launched and he had actively played over a longer period of time until shortly before the collision of the trains."

"Therefore," the statement added, “the suspect is not only charged with moment’s failure," but with "a significantly more serious breach of duty."

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The man denied being distracted by the computer game. But the prosecutor's office said the time period in which he was found to be playing the game meant it could be expected that he was not paying attention to a critical traffic intersection.

The controller gave the trains an incorrect signal and then hit the wrong buttons when issuing a distress signal, meaning it was not heard by the train conductors, the prosecutor's office said.

The trains, carrying about 150 people in all, crashed at high speed on a 4-mile stretch of track between the spa town of Bad Aibling and Kolbermoor, near the Austrian border.

The investigation is continuing. No evidence of technical problems has been found to date.