The body of a 52-year-old man, whom the BJP claimed as its member, was found floating in a pond in Murshidabad district of West Bengal, police said on Tuesday.
Dhormo Hazra was found in the pond close to his village in Taldanga area of the district on Monday, a police officer said.
"The man was missing since Sunday. His body was found with his hands tied," the officer said.
Police have launched an investigation into the incident, but no arrests have been made so far, he said.
Hazra's death has sparked a political blame game, with the BJP accusing the ruling Trinamool Congress (TMC) of orchestrating his killing, a charge rubbished by the party.
"TMC shames humanity, yet again. Another BJP karyakarta killed in the most barbaric manner. In Mamata's regime, West Bengal has become an epitome of violence and brutality. Entire BJP stands firmly with Dhormo Hazra's family in this hour of grief. My deepest condolences," BJP president Amit Shah said in a tweet.
The saffron party had earlier claimed that three of its supporters had been killed before and after the May rural polls in West Bengal.
TMC zila parishad member Shahnaz Begum had denied the allegation and said it was a fallout of a family matter.