A rail traffic controller is to be prosecuted over the train crash that killed 16 people and left more than 50 others injured in Poland on Saturday night.
According to the BBC, two officials on duty at the time have been questioned over the incident and one will be charged with unintentionally causing the crash, which is being described as Poland's worst train disaster in 20 years.
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The official is accused of allowing both trains ended up on the same track near Szczekociny, just north of Krakow, and could face up to eight years in jail.
AP quotes the prosecutor Tomasz Ozimek as saying that the controller has not been charged yet because he is in a state of shock and under doctors' care.
The news agency says that the announcement is the first indication that human error caused the crash.
Alcohol tests on the railway workers on duty were negative, Polish media reportedly said.
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Meanwhile, crash investigators says they have identified the American woman who was among the victims.
AFP says that a spokesman for the US consulate in the southern Polish city of Krakow said the woman's family had been informed, but declined to provide further details.
Poland began two days of mourning for the victims of the crash on Monday, The Warsaw Business Journal says.
It says that Poland's President Bronisław Komorowski, the Prime Minister Donald Tusk, as well as Interior Minister Jacek Cichocki and Minister of Transport Sławomir Nowak visited the scene of the disaster.
Flags are flying at half-mast on public buildings and some news websites were using only black-and-white pictures, the BBC said.
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