The body of Pritam, a resident of Silchar in Assam, was found by the GRP near a bridge near Katoriya station.
A day earlier he had gone missing after he got down from the Awadh-Assam Express, in which he was travelling, at Naogachiya station to lodge a complaint following a tiff with some unknown persons inside the the train, the sources said.
A case of his kidnapping was registered by his uncle Dada Mohan Bhattachary with the Naogachiya rail police station on July 10.
Police sources said Pritam had been killed and his body thrown on the tracks which was traced on the basis of location of his mobile phone.
Raids were on in the area to apprehend those involved in the case. A medical board was constituted by the authorities to do a postmortem on him, the sources said.