Agartala: A "cold-blooded conspiracy was hatched" to murder Tripura's senior journalist Sudip Dutta Bhowmik, the special investigation team probing the killing has found.

Bhowmik was shot dead inside Tripura State Rifles 2nd battalion headquarters at RK Nagar, 18km from here, in West Tripura district on November 21 by rifleman Nandagopal Reang after a purported scuffle with battalion commandant Tapan Debbarma. Both Reang and Debbarma were arrested.

DIG (Northern Range) Arindam Nath, who heads the SIT, told The Telegraph on Saturday that investigations had revealed "a cold-blooded conspiracy" to murder Bhowmik and that they had arrested two more TSR personnel, naik subedar Amit Debbarma and orderly Dharmendra Singh, on Friday night.

They were presented before the chief judicial magistrate's court on Saturday evening and sent to seven-day police custody.

The arrests were made after interrogation of Tapan Debbarma and Reang.

The SIT slapped charges of criminal conspiracy on all four on Saturday, assistant public prosecutor Uttam Banerjee told this correspondent. They will be tried for conspiring to kill Bhowmik under Section 120 (b), in addition to the previous charges of Sections 302, 109 and 27 under the Arms Act. They will be produced before the court on December 1 for further hearing.

The police said two of the four arrested TSR personnel met at least once to conspire to kill the journalist.

Assam probe: The Guwahati-based Kamala Saikia Memorial Trust on Saturday has sent a memorandum to Prime Minister Narendra Modi, seeking a CBI inquiry into the murder of Kamala Saikia and 20 other journalists since 1991. Saikia was abducted from his house in Sivasagar district of Upper Assam on August 9, 1991 and murdered.

In a statement issued on Saturday evening, the trust said journalists have been targeted by militants and other criminals but police have failed to pinpoint the assailants. Hence a CBI inquiry is necessary to punish the killers.