The rucksack of Pritam was found yesterday nearly 300 metres away from the place near Kataria Railway Station where the body of Pritam had been dumped by his killer, sources said.
Police claimed the rucksack could provide vital clues to crack the case.
Bhattacharjee, a research scholar from Assam, had gone missing from Naugachia Railway Station on July 9. His body was recovered on July 17.
Inspector General (railway police) Vinay Kumar said a team of forensic experts was being sent to Naugachia from Patna to examine the rucksack of Pritam.
The certificates of the victim were found in the rucksack, Kumar said, adding that his laptop bag was yet to be recovered.
The Station House Officer (SHO) of Government Railway Police, Naugachia, Manish Kumar was suspended yesterday for his alleged failure to "cooperate" in the investigations into the case relating to the killing.
In place of Kumar, Baidyanath Pathak Vaidic has been appointed as the SHO, Naugachia, GRP.
The police are trying to investigate established gangs operating on the Kathihar-Barauni stretch, which may have links to the case, sources added.
