A bench comprising Chief Justice Sanjoy Karol and Justice Arindam Lodh also handed down life term to another accused who had been acquitted by the trial court in 2016.
Parimal Saha, the then MLA from the Charilam constituency, and his companion Jiten Saha were hacked to death on April 7, 1983 at Office Tilla locality under Bishalgarh police station limits, about 20 kilometres from here.
A complaint was lodged with the police against 25 people in connection with the case. The case dragged on for years before the then Chief Justice of the Tripura High Court Deepak Gupta in 2015 ordered its reopening.
Thirty-three years after the killing, additional district and sessions judge of West Tripura on April 30, 2016, convicted 12 of the 17 accused in the murder case and acquitted five.
Of the seven other accused, six died during trial and one remains absconding