Additional and Session Judge of West Tripura district Kripankar Chakrabarty convicted Sushil Choudhury, the owner and editor of Dainik Ganadoot under sections 302 (murder) and 120(B) (criminal conspiracy) of IPC.
The punishment would be announced on July 17.
Manager of the newspaper, Ranjit Choudhury, proof reader Sujit Bhattacharjee and driver Balaram Ghosh were killed inside the office premises at Palace Compound here.
Police after investigation stated that no outsider was involved in the murders.
According to the prosecution, the manager had threatened to expose illegal activities of the owner, including in brokering of land.
Proof reader Sujit Bhattacharjee, hearing the commotion, rushed to the manager's office on the first floor when he was confronted by the knife-wielding driver. The two of them fought and stabbed each other.
The newspaper owner was also accused of not calling for medical help immediately. The delay resulted in excessive blood loss and the death of the proof reader and driver.