Justice Manas Basu of the Fast Track court, Rampurhat, convicted 20 people for the murder of Dost Mohammed on October 5, 2002.
One of them, a minor, was sent before the Juvenile Justice Board.
According to the prosecution, Mohammad was attacked when he was at a tea-stall with his brother Bajle Rehman in Kamarkhur village of Murarai.
While Bajle managed to escape, the convicts hurled bombs at the victim and injured him with a sharp weapon.
He was taken to Murarai hospital in critical condition where the doctors declared him dead.
Altogether 22 people had been arrested in the case with two acquitted later.
