In August 2006, Vidham Singh, his brother Chob Singh and Kallu were attacked while they were on way to a bank in Allapur village, prosecution said.
While Chob Singh died on the spot, Kallu succumbed to injuries at a hospital, they said.
The robbers also looted two licenced weapons, a gold chain and Rs 30,000 cash, sources said.
Special Judge Sanjay Kumar held Rajedra, Pappu, Chotte, Nanhe, Aram Singh, Muneesh, Rajpal and Suresh guilty and sentenced them.