Sujit Rai (30), president of the Nalasopara branch of the Republican Party of India (RPI) was found dead at Ambadinagar in Nalasopara (East) on Saturday.
There were severe injury marks on his head and neck.
The locals discovered the body and informed the police about the incident.
Rai was a resident of Anant apartment in Nalasopara.
The body was taken to a local hospital where a post mortem will be conducted later, said the police.
The Nalasopara police have registered a case under section 302 (murder) against an unidentified person.
The police said the motive of the murder is yet to be ascertained.
Assistant Police Inspector V L Patil of Nalasopara police station said: “Rai’s wife stays in his hometown while he was staying here with his youngest brother.”
“Rai has three brothers. On Friday evening Rai had called one of his brothers in his village and informed him that some people wanted to kill him and that his life was in danger,” he added.
When his brother tried calling him in the morning, his calls went unanswered, said Patil.