It was a result of technical fault and negligence of the railways, revealed the report of the Special Investigation Team, constituted by the state government to ascertain what caused the accident, an official said Friday.
Saran Superintendent of Police Sudhir Kumar said the Special Investigating Team (SIT) probe report has made it clear that derailment was the result of a technical fault and negligence of railways.
"SIT has come to this conclusion after samples of damaged fastening clips and pieces of rust-stained railway tracks were tested in the Patna forensic science laboratory," Kumar said.
There was no sign of railway tracks blasted or any sabotage, he said.
He said the same samples would be send to the National Metallurgical Laboratory, Jamshedpur, in Jharkhand for tests after the court granted permission for it.
The SIT has recorded the statements of about 45 railway employees in this connection.
The railway's safety panel is also probing the derailment. The Commissioner of Railway Safety (Eastern Circle) P.K. Vajpayee visited the derailment site in Saran last month for investigation.
Twelve bogies of the Delhi-Dibrugarh Rajdhani Express derailed at Bishanpur village near Goldenganj railway station in Chhapra, district headquarters of Saran.
The Bihar government had already ruled out involvement of Maoists in the derailment and blamed poor maintenance of tracks as the cause.