Salehin has been a fugitive since 2015 since he was abducted him from a prison van carrying him to Mymensingh jail after a gun attack in Trishal upazila.
The court did not consider the appeal of Rakib, another death-row convict in the case, as he already died.
Deputy attorney general Biswajit Debnath represented the state.
In 2006, Dhaka Speedy Trial Tribunal sentenced Salehin and Rakib to death in the case and later the High Court (HC) upheld sentence rejecting their appeal.
Rejected by the HC the two appealed the death sentence before the Supreme Court.
Additional attorney general Mehedi Hasan Chowdhury said Goni Gomez, owner of a pharmacy, who had converted to Christian from Muslim, was killed by the JMB men.
Rakib, another accused in the case, was killed in a gunfight with police in 2015.