A deadly head-on collision between two commuter trains in Germany was likely caused by a railway employee's error, prosecutors and police said Tuesday.
Eleven people died and more than 80 were injured when the trains collided Feb. 9 on a stretch of single track near Bad Aibling, southern Germany.
Authorities said they have launched a negligent homicide investigation against the track controller.
The worker is a married 39-year-old who finished his training in 1997, according to a joint press conference by the prosecutor's office in Traunstein and police in Bavaria.
He has not been arrested or identified, but was questioned for hours in the presence of his lawyer after handing himself over to authorities Monday, officials said.
Officials said the "complicated, complex and time-consuming," investigation showed that he gave an incorrect signal to one of the trains and issued an emergency call as soon as he realized his mistake.
"If he would have followed the regulations - acted dutiful - then it would not have come to the collision of the trains," the authorities said in an accompanying statement. "His behavior was not in accordance with the applicable guidelines."
The worker was being kept at an unidentified location and "is not doing well," an official said at the press conference.
He was not believed to be under the influence of alcohol or drugs at the time of the accident.