The murder suspect died during a gun battle at Kosba in Shilaidoho on early Friday, said Kumarkhali Police OC Abdul Khalek.
Shahin Ali, 30, was among eight people suspected of murdering Rakibul Islam, a 32-year-old Malaysia resident who was visiting his hometown in Kumarkhali.
"The criminals started firing at the police, prompting them to fire back. The gang eventually retreated and left behind a bullet-ridden body," said OC Abdul.
Shahin was declared dead at Kushtia General Hospital. His body was later identified by family members and locals.
Rakibul Islam, who he was suspected of killing, was found dead in Kaligonga river on Oct 5, after being reported missing by his family.
Rakibul's father Montu Biswas filed a case with Kumarkhali Police at the start of this week. Police's investigation led to the arrest of Rakibul's wife Naima Sultana and younger brother Rokibul Islam.
The police said Rokibul confessed in court that the he and Naima were having an affair and planned Rakibul's murder by hiring professional killers.